Method of manufacturing color electroluminescent display apparatus and method of bonding light-transmitting substrates

ABSTRACT

An object of the invention is to prolong the seal life of a color EL display apparatus. The initial thickness of a light-transmitting main substrate is larger than a predetermined reference thickness WC. First, a plurality of thin-film EL devices are formed on one surface of the main substrate. Then, a sealing substrate having a concave portion formed in one surface thereof is bonded onto the one surface of the main substrate at predetermined intervals. Then, a protective material for protecting the thin-film EL devices is filled in the gap between the one surface of the main substrate and the sealing substrate. Then, the main substrate is processed so as to have the reference thickness WC. Then, a color filter portion is formed on the other surface of the main substrate. Lastly, a reinforcing substrate is attached to the other surface of the main substrate with the color filter portion in between. Consequently, a color EL display apparatus having a sealing portion of the same structure as that of the currently-used sealing portion is completed.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a method of manufacturing acolor electroluminescent display apparatus applied to various types ofthin-plate display apparatuses, and a method of bondinglight-transmitting substrates used for the same.

[0003] 2. Description of the Related Art

[0004] An electroluminescent (hereinafter, abbreviated as “EL”) displayapparatus is a thin display apparatus capable of matrix display like aliquid crystal display apparatus. The EL display apparatus comprises aplurality of EL devices arranged on a substrate. Each of the EL devicescomprises an EL light emission layer interposed between a pair ofelectrodes, and acts as a picture element of the EL display apparatus.When a so-called high alternating field is generated between the pair ofelectrodes, the EL light emission layer causes electroluminescence, sothat light is emitted from the EL light emission layer. This light isso-called EL light. That is, unlike the liquid crystal displayapparatus, the EL display apparatus is of a self-light-emission-typedisplay apparatus that is constituted only by solid-state devices.Moreover, compared to the liquid crystal display apparatus, the ELdisplay apparatus is high in contrast and excellent in legibility. Sincethe EL display apparatus has the above-mentioned characteristics thatcannot be obtained from the liquid crystal display apparatus, researchthereon is being widely performed. In recent years, research has beenperformed on the achievement of a thin-film EL display apparatus capableof color display. The thin-film EL display apparatus, which is a type ofthe EL display apparatus, uses so-called thin-film EL devices as the ELdevices.

[0005] The applicant has proposed a first prior art regarding theachievement of an EL display apparatus capable of color display inJapanese Examined Patent Publication JP-B2 3-77640 (1991). A color ELdisplay apparatus using thin-film EL devices according to the firstprior art has a structure such that three kinds of EL light emissionlayers that emit light beams of wavelengths of red, green and blue byelectroluminescence, respectively, are arranged in parallel and the ELlight emission layers are each sandwiched between a pair of electrodes.In order to put the color EL display apparatus to practical use, it isnecessary for the EL light emission layers to emit light beams of thewavelengths with a brightness necessary for matrix display. Generally,the wavelength and the brightness of the light emitted from an EL lightemission layer by electroluminescence depends on the material of the ELlight emission layer. Since there are few materials that emit lightbeams of the wavelengths of red, green and blue with the above-mentionedbrightness, it is difficult to realize the color EL display apparatus.

[0006] A second prior art regarding the achievement of a color ELdisplay apparatus is disclosed in Japanese Unexamined Patent PublicationJP-A 64-40887 (1989). The color EL display apparatus of this prior artincludes a plurality of thin-film EL devices of a double insulationstructure including a light emission layer that emits so-called whitelight by electroluminescence, and a plurality of organic color filterseach transmitting light of the wavelength of only one of red, green andblue. The color filters are each placed directly on one electrode of thepair of electrodes of each thin-film EL device. The white light emittedfrom each EL device is divided into spectra by the color filters.Consequently, light beams of the wavelengths of red, blue and green exitfrom the color EL display apparatus.

[0007] The thin-film EL devices of the double insulation structure inwhich thin-film insulation layers are interposed between the electrodesand the light emission layers has a structure such that a multiplicityof thin film pieces are laminated. In forming the film pieces, a defectsuch as a pinhole is sometimes caused in the film pieces. In the casewhere the insulation layer has a defect such as a pinhole, when the highalternating field is created between the pair of electrodes of thethin-film EL devices, an electrical breakdown is caused at the pinholeand in the vicinity thereof, so that a microdischarge is caused. Thereare cases where the color filters on the electrodes deteriorates andbreaks due to the microdischarge.

[0008] As a third prior art regarding the achievement of a color ELdisplay apparatus, Japanese Unexamined Patent Publication JP-A 64-40888(1989) discloses an art to prevent the above-mentioned deterioration andbreakage of the color filters. FIG. 20 is an enlarged partialcross-sectional view of a color EL display apparatus 1 according to thisprior art. The color EL display apparatus 1 comprises a main substrate3, a light-transmitting substrate 4, a plurality of thin-film EL devices5 of the double insulation structure, a plurality of color filters 6 anda sealing portion 7. The thin-film EL devices 5 are arranged on onesurface 9 of the main substrate 3. The color filters 6 are arranged onone surface 10 of the light-transmitting substrate 4. The main substrate3 and the light-transmitting substrate 4 are disposed so that thesurfaces 9 and 10 are opposed with a predetermined gap in between. Thesealing portion 7, which is so-called passivation protecting means, isdisposed between the main substrate 3 and the light-transmittingsubstrate 4.

[0009] The method of manufacturing the color EL display apparatus 1 willbriefly be described below. First, a plurality of lower electrodes 11which are thin film strips are formed on the one surface 9 of thesubstrate 3. Then, a lower insulation layer 12, a light emission layer13 and an upper insulation layer 14 are successively laminated in thisorder on all the lower electrodes 11. Then, a plurality of upperelectrodes 15 which are thin film strips are formed on the upperinsulation layer 14. The upper electrodes 15 each transmit light. Thedirection of length of the lower electrodes 11 and the direction oflength of the upper electrodes 15 are perpendicular to each other whenviewed from the direction of the normal 16 to the one surface 9 of thesubstrate 3. The portions where the lower electrodes 11 and the upperelectrodes 15 intersect when viewed from the direction of the normal 16are the thin-film EL devices 5. In order to improve the crystallinity ofthe light emission layer 13, after the light emission layer 13 is formedor after the upper insulation layer 14 is formed, annealing is performedin a vacuum or in an inert gas.

[0010] Then, the color filters 6 are formed on the one surface 10 of thelight-transmitting substrate 4. Then, the substrate 3 and thelight-transmitting substrate 4 are bonded by an epoxy resin 17 so thatthe surfaces 9 and 10 are opposed with the predetermined gap in between.Lastly, in order to form a protective material layer 18, the gap betweenthe substrate 3 and the light-transmitting substrate 4 is filled with agaseous or a liquid protective material. The epoxy resin 17 and theprotective material layer 18 constitute the sealing portion 7. By theabove-described process, the color EL display apparatus is completed.

[0011] Generally, the inactivation protecting means, that is, thesealing portion 7 is provided for shielding the thin-film EL devicesfrom the atmosphere to thereby stabilize the thin-film EL devices andprotecting the thin-film EL devices from mechanical failures. Aso-called seal life which is one of the greatest characteristics oftypical EL display apparatuses depends on the structure of the sealingportion.

[0012] A sealing portion currently used in a typical thin-film ELdisplay apparatus is formed by use of a sealing substrate and a mixtureliquid of silica gel and silicone oil. The process of forming thecurrently-used sealing portion will be described below. The typicalthin-film EL display apparatus comprises a plurality of EL devicesarranged on one surface of a substrate. First, a concave portion with adepth of 300 to 500 μm is formed in one surface of the sealingsubstrate. Then, the sealing substrate and the substrate are bondedtogether so that the concave portion is opposed to the one surface ofthe substrate and that a filling hole is left. Then, the gap between thesubstrate and the sealing substrate is evacuated, and the mixture liquidis filled into the gap. Lastly, the filling hole is sealed, whichcompletes the currently-used sealing portion.

[0013] The silica gel absorbs moisture intruding into the gap. Thesilicone oil circulates the silica gel in the gap and cools the ELdevices. Consequently, the EL devices are protected from the influenceof moisture and the like. The seal life obtained from the currently-usedsealing portion is not less than 50 thousand hours.

[0014] In the color EL display apparatus 1 of the third prior art, thelight-transmitting substrate 4 is used instead of the sealing substrate,and the protective material is filled into the gap between the substrate3 and the light-transmitting substrate 4 to form the sealing portion 7.However, in the color EL display apparatus 1, in order to ensure aviewing angle sufficient for practical use, it is necessary that the gapbetween the substrate 3 and the light-transmitting substrate 4 beminimized. Consequently, the gap between the substrate 3 and thelight-transmitting substrate 4 is frequently a fraction of the width ofthe gap in the currently-used sealing portion. Therefore, the seal lifeof the color EL display apparatus 1 is reduced to a fraction of that ofthe EL display apparatus having the currently-used sealing portion.Further, in the color EL display apparatus 1, since the silica gelenters the gap between the EL devices and the color filters, blur anddistortion are caused in the display.

[0015] As a fourth prior art regarding the achievement of a color ELdisplay apparatus, Japanese Unexamined Patent Publication JP-A 64-40888(1989) further discloses an art to form color filters while employingthe currently-used sealing portion. A color EL display apparatusaccording to the fourth prior art has a structure such that a pluralityof EL devices are arranged on one surface of a substrate, a plurality ofcolor filters are arranged on the other surface of the substrate and theabove-described currently-used sealing portion is disposed on the onesurface of the substrate. However, in the color EL display apparatus ofthe fourth prior art, since the thickness of the substrate is 1 to 2 mm,color displacements of the display are apt to be large and it isdifficult to increase the degree of precision of the thin-film ELdevices. Moreover, since the substrate thickness of the EL displayapparatus is generally not less than 1.1 mm, the viewing angle of thecolor EL display apparatus of the fourth prior art is apt to beextremely narrow compared to those of the EL display apparatuses of thefirst to the third prior arts.

[0016] In order to improve the viewing angle of the color EL displayapparatus of the fourth prior art, it is necessary that the thickness ofthe substrate be smaller than the thickness of general substrates. Whenthe thickness of the substrate is reduced, in the steps of formingvarious thin films and the step of photoprocess in the process ofmanufacturing the color EL display apparatus of the fourth prior art, itis difficult to ensure a substrate strength necessary for the steps andto handle the substrate. At the same time, there is a possibility thatthe substrate cracks when the gap is evacuated in order to fill themixture liquid into the gap. Because of these problems, it is difficultto reduce the thickness of the color EL display apparatus of the fourthprior art so as to be smaller than the thickness of general substrates.

[0017] Moreover, there are cases where a photo-setting resin is used,for example, for bonding a light-transmitting substrate having the colorfilters disposed thereon and the other substrate. However, since thecolor filters intercept light necessary for hardening the photo-settingresin such as ultraviolet rays, the photo-setting resin cannot harden inthe area where the color filters are disposed.

[0018] Moreover, in the case where two light transmitting substrates arebonded together by filling the gap between the substrates with anadhesive, when there are portions where the adhesive is absent, that is,when bubbles are formed, the refractive index of the portions isdifferent from that of the surrounding portions, so that theconfigurations of the bubbles appear on the display screen when adisplay is provided. This degrades the display quality.

[0019] In the case where two light-transmitting glass substrates arebonded together, a conventionally used method is such that an adhesiveis thinly applied onto the surface of one glass substrate and then, thetwo substrates are brought into intimate contact with each other.However, in the case where an adhesive is applied, it cannot be helpedthat slight wavy patterns are formed on the surface. When the unevenportions of the wavy patterns are in contact with the substrate, airgaps are formed between the substrate and the adhesive. When there is noplace for the air in the air gaps to escape into, the air gaps are leftas bubbles.

[0020] As a method of bonding two substrates without such bubbles beingformed, for example, Japanese Unexamined Patent Publication JP-A63-18326 (1988) discloses a method in which bubbles are blown off by aspinner rotation after the substrates are bonded. Japanese UnexaminedPatent Publication JP-A 9-278497 (1997) discloses a method in which whensubstrates are bonded together, the substrates are inclined by anapparatus for controlling the angles of the substrates in order that nobubbles are formed. Japanese Unexamined Patent Publication JP-A 3-126646(1991) discloses a method in which when an adhesive is applied to thesubstrate, the thickness of the adhesive is controlled so as tomonotonously increase from one end to the other end to thereby preventthe formation of bubbles when the substrates are bonded together.Japanese Unexamined Patent Publication JP-A 6-349962 (1994) discloses abonding method in which a central portion of glass formed so that thecentral portion thereof is higher than the other portions thereof ismelted to bond the two substrates to thereby prevent the formation ofbubbles. However, the bonding methods disclosed in the prior arts allrequire separate apparatuses having complicated structures, whichincreases the manufacturing cost. Therefore, an easier method is desiredin order to increase industrial use.

[0021] Moreover, when two substrates are bonded together by dropping aliquid hardening resin on one surface of a thin substrate, there arecases where the dropped resin concaves the thin substrate and theconcaved portion is left as a distortion of the EL display screen todegrade the display quality.

[0022] Moreover, glass substrates generally have local and smallasperities. FIG. 21 is a plan view schematically showing conditions inbonding substrates having such local concave portions. When thesubstrates are brought into intimate contact with each other so that aliquid hardening resin spreads between the substrates, as shown in FIG.21, although the speed at which the resin spreads is constant in thearea where a local concave portion P is absent, the resin spreadingspeed is lower in the local concave portion P than in the periphery.Consequently, as shown in FIG. 21, the resin spreads over the peripheryof the concave portion P faster in the vicinity of the concave portionP, so that the periphery is filled with the resin without the resinbeing spread over the concave portion P. As a result, a bubble is leftin the concave portion P.

SUMMARY OF THE INVENTION

[0023] An object of the invention is to provide a method ofmanufacturing a color EL display apparatus having a long seal life, awide viewing angle and improved display quality, and alight-transmitting substrate bonding method used for the manufacturingmethod.

[0024] The invention provides a method of manufacturing a color ELdisplay apparatus comprising the steps of:

[0025] forming a plurality of EL devices in which an EL light emissionlayer is interposed between a pair of electrodes, on one surface of afirst light-transmitting substrate having a thickness larger than apredetermined reference thickness;

[0026] attaching a second substrate to the one surface of the firstsubstrate with a predetermined gap in between;

[0027] filling a material for protecting the EL devices, into a gapbetween the one surface of the first substrate and the second substrate;

[0028] processing the first substrate so as to have the referencethickness; and

[0029] attaching color filters each capable of transmitting light of apredetermined wavelength to the other surface of the first substrate.

[0030] According to the invention, the light emitted from the EL displaydevices exits from the color EL display apparatus manufactured by theabove-described method after being transmitted by the color filters. Bythe color filters being capable of transmitting light of differentwavelengths, so-called multicolor light emission is enabled.

[0031] In the above-described manufacturing method, after the firstsubstrate and the second substrate are bonded together and the materialis filled into the gap between the substrates, the first substrate isprocessed so as to have the reference thickness. The reference thicknessis, for example, smaller than that of the above-described prior artcolor EL apparatuses. Therefore, in the process of manufacturing thecolor EL display apparatus, the thickness of the first substrate islarger than the reference thickness during a period from the EL deviceforming process to the material filling process. Consequently, duringthe period, the strength of the first substrate is greater than that ofa substrate of the reference thickness. Therefore, the first substrateis prevented from warping in the EL device forming process, and thehandling of the first substrate in the forming process is facilitated.Further, the first substrate is prevented from cracking in the materialfilling process. Thus, the manufacture of the color EL display apparatusis easy compared to the case where the thickness of the first substrateis the reference thickness from the start of the manufacturing process.

[0032] Further, in the color EL display apparatus of the invention, thestructure of the sealing portion comprising the second substrate and thematerial is substantially the same as the structure of thecurrently-used sealing portion of typical color EL display apparatuses.Therefore, the seal life of the color EL display apparatus of theinvention is long compared to that of the color EL display apparatus ofthe above-described third prior art.

[0033] Consequently, a color EL display apparatus having a seal lifesufficient for practical use can easily be manufactured.

[0034] Moreover, in the invention it is preferable that the referencethickness is not more than 1.2 times the width of an interval betweenone electrodes of the pairs of electrodes in two adjacent EL devices.

[0035] According to the invention, the reference thickness, that is, theafter-processing thickness of the color EL display apparatusmanufactured by the manufacturing method of the invention is not morethan 1.2 times the width of the interval. Consequently, the viewingangle of the color EL display apparatus is not less than 160°. As aresult, the viewing angle of the color EL display apparatus issufficient for practical use.

[0036] Moreover, in the invention it is preferable that the referencethickness is not less than 25 μm and not more than 200 μm.

[0037] According to the invention, the reference thickness, that is, theafter-processing thickness of the first substrate of the color ELdisplay apparatus manufactured by the manufacturing method of theinvention is not less than 25 μm and not more than 200 μm. This is forthe following reason: At present, the electrode pitch of a prior artdirect matrix color EL display apparatus featuring high-resolutiondisplay is not less than 2 per millimeter. Therefore, the distancebetween the electrodes of two adjacent EL devices in the prior art colorEL display apparatus is approximately 50 to 150 μm. Therefore, by thereference thickness being not more than 200 μm, when the distancebetween the electrodes of adjacent EL devices in the color EL displayapparatus manufactured by the manufacturing method of the invention isthe same as that in the prior art color EL display apparatus, theviewing angle dependency of the color EL display apparatus issignificantly improved compared to that of the prior art color ELdisplay apparatus. The thinner the first substrate is, the higher thepossibility is that the first substrate is damaged in the manufacturingprocess after the processing of the first substrate. Considering theprocessing accuracy of the first substrate, it is necessary to considerthat there is an error of ±10 μm in the after-processing thickness ofthe first substrate. From these, since there is no margin when thereference thickness is less than 25 μm, the reference thickness is setto not less than 25 μm.

[0038] Moreover, in the invention it is preferable that the referencethickness is not less than 50 μm and not more than 100 μm.

[0039] According to the invention, the reference thickness, that is, theafter-processing thickness of the first substrate of the color ELdisplay apparatus manufactured by the manufacturing method of theinvention is not less than 50 μm and not more than 100 μm. This is forthe following reason: In the case where the reference thickness is notmore than 50 μm, when the actual production of the color EL displayapparatus is considered, it is difficult to ensure processing accuracyin the processing of the first substrate. Moreover, in this case, whenthe actual production of the color EL display apparatus is considered,handling of the first substrate is difficult after the processing of thefirst substrate. Therefore, the reference thickness is set to not lessthan 50 μm in order to ensure the processing accuracy of the firstsubstrate and to facilitate the handling of the first substrate.Moreover, considering the electrode pitch of currently-used EL panels,the reference thickness is set to not more than 100 μm in order toobtain a viewing angle of 80° at the electrode pitch. The viewing angleof 80° is required when the color EL display apparatus is used as thedisplay of a personal computer for private use.

[0040] Moreover, in the invention it is preferable that the secondsubstrate has a thickness of 0.8 mm or more.

[0041] According to the invention, it is preferable that the thicknessof the second substrate is not less than 0.8 mm. This is for thefollowing reason: The second substrate not only forms a gap into whichthe material is filled but also suppresses the warp of the firstsubstrate due to the internal stress in the EL devices during and afterthe processing of the first substrate. Moreover, a concave portion isfrequently formed in the second substrate in order to maximize the gapinto which the material is filled. Further, the second substrate isfrequently made of a glass material. When the thickness of the secondsubstrate is not less than 0.8 mm, the warp of the first substrate cansurely be suppressed even when the second substrate is made of a glassmaterial and has a concave portion formed therein.

[0042] Moreover, in the invention it is preferable that the methodfurther comprises a step of attaching a third light-transmittingsubstrate to the other surface of the first substrate with the colorfilters in between.

[0043] According to the invention, in the color EL display apparatusmanufacturing method, lastly, the third substrate is further attached tothe other surface of the first substrate. Consequently, the colorfilters are protected by being sandwiched between the first substrateand the third substrate. Moreover, by further attaching the thirdsubstrate, the overall mechanical strength of the color EL displayapparatus can be made greater than that in the case where the thirdsubstrate is not attached.

[0044] Moreover, in the invention it is preferable that the thirdsubstrate has a thickness of 0.5 mm or more.

[0045] According to the invention, the thickness of the third substrateis not less than 0.5 mm. This is for the following reason: Typically, acolor EL display apparatus is frequently housed in a box together with adriving IC for driving the color EL display apparatus to form aso-called display unit. The display unit manufacturing process includesthe step of connecting the tab of the driving IC to the electrodes ofthe EL devices and the step of placing the color EL display apparatus inthe box. When the thickness of the third substrate is not less than 0.5mm, the entire color EL display apparatus manufactured by theabove-described manufacturing method can have a mechanical strengthnecessary for the display unit manufacturing process.

[0046] Consequently, the color EL display apparatus has a seal lifesufficient for practical use and can easily be manufactured.

[0047] The invention provides a method of manufacturing a color ELdisplay apparatus, comprising the steps of:

[0048] preparing EL devices in which a first light-transmittingelectrode, an EL light emission layer and a second electrode are formedon one surface of a light-transmitting EL-device substrate and EL lightis emitted from the other surface of the EL-device substrate, and acolor filter substrate where color filters are disposed on one surfaceof a light-transmitting substrate; and

[0049] filling a thermosetting resin into a gap between the othersurface of the EL-device substrate and the surface of the color filtersubstrate where the color filters are disposed, and then thermallysetting the thermosetting resin to bond the color filter substrate andthe EL-device substrate.

[0050] According to the invention, a thermosetting resin is filled intothe gap between the other surface of the EL-device substrate and thesurface of the color filter substrate where the color filters aredisposed, and then, the substrates are heated to harden thethermosetting resin, thereby bonding the color filter substrate and theEL-device substrate. Conventionally, since a photo-setting resin is usedfor the bonding of the color filter substrate and the EL-devicesubstrate, the photo-setting resin cannot be hardened in an area wherethe color filters are disposed. However, in the invention using athermosetting resin, the color filter substrate and the EL-devicesubstrate can be bonded by hardening the thermosetting resin by heatingeven in the area where the color filters are disposed. Consequently, thecolor filter substrate and the EL-device substrate can be bonded throughan adhesive layer over the entire surface where the color filters aredisposed, so that a sufficient bonding strength is obtained.

[0051] The invention provides a method of bonding two substrates atleast one of which is a light-transmitting substrate, the methodcomprising the steps of dropping a liquid hardening resin on onesubstrate so as to convexly bulge; and

[0052] subsequently bring the two substrates into intimate contact sothat the liquid hardening resin is spread to fill a gap between thesubstrates and be hardened.

[0053] According to the invention, the liquid hardening resin is droppedon one substrate so as to convexly bulge, that is, in a conical shapehaving one convex portion, and then, the two substrates are brought intointimate contact with the other substrate being pressed against theliquid hardening resin on the one substrate. At this time, since theliquid hardening resin convexly bulges, the liquid hardening resin andthe other substrate are in contact at one point at the top of theportion of the dropped liquid hardening resin, and by bringing thesubstrates into intimate contact, the liquid hardening resin is radiallyspread from the top to fill the gap between the substrates. By theconvex liquid hardening resin portion being thus spread, no air gap isformed in the resin, so that the resin can be filled in the gap betweenthe substrates with the formation of bubbles being prevented. The twosubstrates can be bonded by hardening the liquid hardening resin afterthe resin is filled. By such an easy method, the substrates can bebonded without any bubbles being mixed, so that the manufacturing costcan be reduced.

[0054] The invention provides a method of bonding two substrates atleast one of which is a light-transmitting substrate, comprising thesteps of:

[0055] dropping a liquid hardening resin onto each of the two substratesso as to convexly bulge; and

[0056] subsequently bring the two substrates into intimate contact sothat tops of resin portions on the substrates are in contact with eachother and the liquid hardening resin is spread to fill a gap between thesubstrates and is hardened.

[0057] According to the invention, when the two substrates are broughtinto intimate contact with each other so that the tops of the portionsof the liquid hardening resin dropped on the two substrates so as toconvexly bulge are in contact with each other, the substrates areconnected at one resin portion, so that when the substrates are broughtinto intimate contact, the liquid hardening resin is radially spreadfrom one resin portion and the resin is filled in the gap between thesubstrates without any bubbles being formed. By thus dropping the liquidhardening resin onto both substrates, compared to the case where theliquid hardening resin is dropped onto only one substrate, the portionof the substrate with which the dropped resin is in contact is smalleven when the amount of application is the same, so that the resin canbe filled in the gap between the substrates with the mixture of bubblesbeing further prevented. Moreover, the manufacturing cost can be reducedby such an easy bonding method.

[0058] The invention provides a method of bonding two substrates atleast one of which is a light-transmitting substrate, comprising thesteps of:

[0059] dropping a liquid hardening resin onto one substrate at aplurality of points along a straight line or a zigzag line; and

[0060] subsequently bringing the two substrates into intimate contact sothat the liquid hardening resin is spread to fill a gap between thesubstrates and is hardened.

[0061] According to the invention, the two substrates are brought intointimate contact after the liquid hardening resin is dropped at aplurality of points along a straight line or a zigzag line, so that theliquid hardening resin can effectively be spread over the entiresubstrate even when the substrate is rectangular. Moreover, in theinvention, although the liquid hardening resin is dropped at a pluralityof points, since the liquid hardening resin portions are arranged alonga straight line or a zigzag line, a gap is prevented from being leftbetween the resin portions when the resin is spread. Consequently, theformation of bubbles is prevented and the resin can substantiallyuniformly be applied over the entire surface even when the substrate isrectangular. Moreover, the manufacturing cost can be reduced by such aneasy bonding method.

[0062] In the invention it is preferable that when being heated, theliquid hardening resin has a viscosity lower than that at an ordinarytemperature, and

[0063] that a force is exerted on the substrates so that the resinbetween the substrates is spread while the substrates are being heated.

[0064] According to the invention, by heating the two substrates whenthe substrates are brought into intimate contact, the viscosity of theliquid hardening resin decreases, so that the substrates can be broughtinto intimate contact with the resin being thinly and uniformly spreadbetween the substrates. Since the viscosity is high when the resin isdropped, the resin can suitably be dropped so as to convex. In the casewhere the viscosity is low when the resin is dropped, since the resinthinly spreads over the substrates, an air gap is formed when thesubstrates are brought into intimate contact, so that bubbles areformed. In the invention, however, by dropping the resin in a highviscosity condition, the resin can suitably be dropped so as to convexin a conical shape, so that the resin can be spread without any bubblesbeing formed. Moreover, by exerting a force on the substrates whileheating the substrates, the resin can thinly be filled in the gapbetween the substrates.

[0065] In the invention it is preferable that when the EL-devicesubstrate and the color filter substrate are bonded together, a liquidthermosetting resin is dropped on one substrate so as to convexly bulge,the two substrates are brought into intimate contact so that thethermosetting resin is spread to fill the gap between the substrates,the substrates are fixed by a photo-setting resin at a portion wherecolor filters are not disposed under a condition where the EL-devicesubstrate and the color filter substrate are positioned, and then, thesubstrates are heated to harden the thermosetting resin, thereby bondingthe two substrates.

[0066] According to the invention, by bringing the two substrates intointimate contact after the liquid thermosetting resin is dropped ontoone substrate so as to convex, the liquid thermosetting resin can befilled in the gap between the substrates without any bubbles beingformed. The photo-setting resin is applied onto the portion between thesubstrates where the color filters are not disposed, and after theEL-device substrate and the color filter substrate are positioned byaligning the electrode pattern of the EL devices and the color filterpattern of the color filter substrate, the photo-setting resin ishardened by applying light, thereby temporarily fixing the EL-devicesubstrate and the color filter substrate. Then, the thermosetting resinis hardened by heating, so that the substrates are bonded. Thus, sincethe resin can thermally be hardened after the substrates are positionedat an ordinary temperature and temporarily fixed, a problem iseliminated such that it is necessary to position the substrates whilehardening the resin by heating.

[0067] In the invention it is preferable that when the EL-devicesubstrate and the color filter substrate are bonded together, athermosetting resin is dropped onto each of the substrates so as toconvexly bulge, the two substrates are brought into intimate contact sothat tops of resin portions on the substrates are in contact with eachother to thereby spread the thermosetting resin to fill the gap betweenthe substrates, the substrates are fixed by a photo-setting resin at aportion where the color filters are not disposed under a condition wherethe EL-device substrate and the color filter substrate are positioned,and then, the substrates are heated to harden the thermosetting resin,thereby bonding the substrates.

[0068] According to the invention, by bringing the two substrates intointimate contact so that the tops of the portions of the liquidthermosetting resin dropped on the EL-device substrate and the colorfilter substrate so as to convex are in contact, the resin can be filledin the gap between the substrates with the mixture of bubbles being moresurely prevented. Moreover, since the color filter substrate and theEL-device substrate are temporarily fixed by the photo-setting resinunder a condition where the two substrates are positioned at an ordinarytemperature, it is unnecessary to perform positioning when the resin isthermally hardened.

[0069] In the invention it is preferable that when the EL-devicesubstrate and the color filter substrate are bonded together, athermosetting resin is dropped so as to convexly bulge on one substrateat a plurality of points along a straight line or a zigzag line, the twosubstrates are brought into intimate contact to spread the thermosettingresin so as to fill a gap between the substrates, the substrates arefixed by a photo-setting resin at a portion where the color filters arenot disposed under a condition where the EL-device substrate and thecolor filter substrate are positioned, and then, the substrates areheated to harden the thermosetting resin, thereby bonding thesubstrates.

[0070] According to the invention, since the liquid thermosetting resinis dropped on one substrate at a plurality of points along a straightline or a zigzag line, the liquid thermosetting resin can effectivelyand uniformly be filled in the gap between the two substrates withoutany bubbles being formed even when the substrates are rectangular.Moreover, since the color filter substrate and the EL-device substrateare temporarily fixed by the photo-setting resin at an ordinarytemperature in a condition where the substrates are positioned, it isunnecessary to perform positioning when the resin is thermally hardened.

[0071] In the invention it is preferable that the liquid thermosettingresin is lower in viscosity when heated than at an ordinary temperature,and

[0072] that when the substrates are heated, a force is exerted on thesubstrates so that the resin between the substrates is spread.

[0073] According to the invention, when the resin is dropped onto thesubstrate at an ordinary temperature, since the viscosity is high, theresin can suitably be dropped so as to convexly bulge. Since theviscosity of the liquid hardening resin decreases when the substratesare heated, the resin is thinly and uniformly spread to fill the gapbetween the substrates, and when the substrates are further heated tothe hardening point, the liquid thermosetting resin is hardened, so thatthe color filter substrate and the EL-device substrate are bonded. Thus,since the thickness of the adhesive layer is decreased, the viewingangle deterioration due to color displacements can be prevented.

[0074] The invention provides a method of bonding two substrates atleast one of which is a light-transmitting substrate, comprising thesteps of:

[0075] dropping a liquid hardening resin on a surface of one substrateso as to convexly bulge;

[0076] directing the surface where the resin is dropped, downward so asto face a surface of the other substrate; and

[0077] bonding the substrates to each other so that the resin is spreadto fill a gap between the substrates and is hardened.

[0078] According to the invention, since the liquid hardening resin isdropped onto only one surface, the manufacturing cost can be reduced,and since the substrates are bonded together with the resin droppedsurface facing downward, even a low-viscosity resin can convexly bebulged effectively to bond the substrates together. Consequently, alow-viscosity resin can be used, the substrates are not distorted evenwhen the substrates are thin, and the substrates can be bonded by thinlyand uniformly spreading the resin between the substrates without anybubbles being formed.

[0079] The invention provides a method of bonding two substrates atleast one of which is a light-transmitting substrate, comprising thesteps of:

[0080] interposing a liquid hardening resin between the substrates;

[0081] spreading the liquid hardening resin between the substrates byuse of a capillary phenomenon of the resin; and

[0082] hardening the resin thereafter.

[0083] According to the invention, the liquid hardening resin is spreadto fill the gap between the substrates by the capillary phenomenon. Thatis, since the gap between the substrates is extremely small, when theliquid hardening resin is interposed between the substrates, the resinspreads over the entire surfaces of the substrates by the capillaryphenomenon due to the surface tension of the resin. Since the surfacetension causes a force to act in a direction that brings the substratesinto intimate contact, a force is exerted in the direction that bringsthe two substrates into intimate contact with each other without anexternal force being exerted on the substrates. When the resin isdropped onto the surface of the substrate and the two substrates arebonded together, the resin dropped portion concaves when the substrateis thin. However, since resin is discharged from the concaved resindropped portion in the process of spread of the resin to the peripherydue to the capillary phenomenon, the concave is reduced at the resindropped portion, so that the substrate becomes flat. As the method ofinterposing the resin between the substrates, a method in which theresin is dropped onto the peripheries of two substrates being inintimate contact and the resin is spread between the substrates can beused in addition to the method in which the resin is dropped on thesurface of the substrate and the substrates are bonded together.

[0084] In the invention it is preferable that the liquid hardening resinis a thermosetting resin, and a viscosity of the resin at an ordinarytemperature is higher than that of the resin thermally hardened.

[0085] According to the invention, by using a thermosetting resin whoseviscosity at an ordinary temperature is higher than that of thethermally hardened resin, the viscosity is high when the resin isdropped, so that the resin can effectively be dropped so as to convexlybulge. When the two substrates are bonded together under this conditionand heated, the viscosity of the resin between the substrates decreases,so that the resin is thinly spread between the substrates. When thesubstrates are further heated to the hardening temperature, thesubstrates can be bonded with the resin being thermally hardened in athinly spread condition. Thus, the substrates can be bonded by thinlyspreading the resin between the substrates with the mixture of bubblesbeing surely prevented.

[0086] In the invention it is preferable that a spacer of apredetermined grain diameter is interposed between the substrates.

[0087] According to the invention, since the spacer of the predeterminedgrain diameter is interposed between the substrates, a predetermineddistance can be maintained between the substrates. When the resinbetween the substrates spreads, a force acts by the surface tension in adirection that brings the substrates into intimate contact as mentionedabove. However, when the substrates are in absolute contact, the resinis prevented from spreading. On the contrary, according to theinvention, the substrates are prevented from being in absolute contactby interposing the spacer between the substrates, so that the resin cansmoothly be spread between the substrates.

[0088] In the invention it is preferable that the spacer is fixed to thesurface of one substrate in advance, and the substrates are bondedtogether thereafter.

[0089] According to the invention, since the spacer is fixed to thesurface of one substrate in advance and the substrates are bondedtogether thereafter, the productivity is excellent. Moreover, since thespacer is fixed in advance, the spacer can be prevented from droppingwhen the substrates are bonded together.

[0090] In the invention it is preferable that the grain diameter of thespacer is not less than 10 μm.

[0091] According to the invention, the grain diameter of the spacer isnot less than 10 μm. When there is a local concave portion in thesurface of the substrate and the difference between thesubstrate-to-substrate distance at the concave portion and thesubstrate-to-substrate distance at the periphery thereof is large, thespeed of spread of the resin is different between at the local concaveportion and at the periphery, so that a bubble is left in the localconcave portion. In the invention, by interposing the spacer with agrain diameter of not less than 10 μm, the difference insubstrate-to-substrate distance between at the local concave portion andat the periphery thereof can be reduced, so that the resin substantiallyuniformly spreads. As a result, the formation of bubbles can be surelyprevented.

[0092] In the invention it is preferable that when an area of a rangebetween the substrates to be filled with the resin is S and the graindiameter of the spacer is d, an amount D of the liquid hardening resininserted between the substrates is selected so as to fall within thefollowing range:

S·d<D<S·(d+12 μm).

[0093] According to the invention, the amount of the dropped resin isselected so as to fall within the above-mentioned range. When the amountof the dropped resin is too large, the resin is filled in the entire gapbetween the substrates before the resin is sufficiently discharged fromthe resin dropped portion, so that the spread of the resin due to thecapillary phenomenon stops. Then, excessive resin is left in the resindropped portion and causes a distortion in the substrate as a concave.When the amount of the dropped resin is too small, the resin cannotcompletely be filled in the gap to be filled with the resin. Therefore,it is necessary that an appropriate amount of resin be filled betweenthe substrates. Since the substrate-to-substrate distance is maintainedconstant by interposing the spacer between the substrates, ideally, theamount D of the resin inserted between the substrates is

D=S·d.

[0094] When the resin of the amount satisfying the expression isinserted between the substrates, an appropriate amount of resin isfilled in the gap between the substrates, so that no concave is causedin the resin dropped portion and no bubbles are formed. However, sincethere are local asperities on the surfaces of the substrates inactuality, it is necessary that the amount of the dropped and insertedresin vary. As a result of an examination, the inventor found that whenthe amount satisfies the following condition, only a distortion thatbecomes no problem is caused although the amount is larger than theideal amount:

D<S·(d+12 μm).

[0095] Moreover, to fill the range between the substrates to be filledwith the resin, the resin of an amount larger than the ideal amount isnecessary. Therefore, it is necessary that the amount D of the resin tobe inserted satisfy the following condition:

S·d<D.

[0096] In the invention it is preferable that one of the two substratesis a light-transmitting EL-device substrate, the El device substrate,having a first light-transmitting electrode, an EL light emission layerand a second electrode formed on one surface thereof, and emitting ELlight from the other surface; and

[0097] that the other substrate of the two substrates is alight-transmitting color filter substrate and has color filters disposedon one surface thereof.

[0098] According to the invention, by bonding the EL-device substrateand the color filter substrate by the above-described substrate bondingmethods, an EL display apparatus can be manufactured in which thedistortion of the substrates and the formation of bubbles are preventedand the display quality is not deteriorated.

BRIEF DESCRIPTION OF THE DRAWINGS

[0099] Other and further objects, features, and advantages of theinvention will be more explicit from the following detailed descriptiontaken with reference to the drawings wherein:

[0100]FIG. 1 is a cross-sectional view of a color EL display apparatus31 manufactured by a color EL display apparatus manufacturing methodaccording to a first embodiment of the invention;

[0101]FIG. 2 is a plan view of the color EL display apparatus 31;

[0102]FIG. 3 is a schematic view of a cross section of a typicaltwo-substrate-bonded-type color EL panel;

[0103]FIG. 4 is a cross-sectional view of a color EL display apparatus91 manufactured by a color EL display apparatus manufacturing methodaccording to a second embodiment of the invention;

[0104]FIG. 5 is a plan view of the color EL display apparatus 91;

[0105]FIG. 6 is a cross-sectional view of a color EL display apparatus111 manufactured by a color EL display apparatus manufacturing methodaccording to a third embodiment of the invention;

[0106]FIG. 7 is a plan view of the color EL display apparatus 111;

[0107]FIG. 8 is a cross-sectional view showing a color EL displayapparatus 220 manufactured by a color EL display apparatus manufacturingmethod according to a fourth embodiment of the invention;

[0108]FIG. 9 is a cross-sectional view showing a color filter substrate222 and an EL-device substrate 221;

[0109]FIG. 10 is a cross-sectional view showing a condition in which thecolor filter substrate 222 and the EL-device substrate 224 are bondedtogether;

[0110]FIGS. 11A and 11B are plan views showing a condition in whichresin is dropped onto the EL-device substrate 224;

[0111]FIG. 12 is a cross-sectional view showing a condition of the colorEL display apparatus 220 at the time of heating;

[0112]FIG. 13 is a plan view showing a condition in which athermosetting resin 333 is dropped onto the EL-device substrate 224 in acolor EL display apparatus manufacturing method according to a fifthembodiment of the invention;

[0113]FIG. 14 is a cross-sectional view showing a condition in which thecolor filter substrate 222 and the EL-device substrate 224 are bondedtogether in a color EL display apparatus manufacturing method accordingto a sixth embodiment of the invention;

[0114]FIG. 15 is a cross-sectional view showing a color EL displayapparatus 320 manufactured by a light-transmitting substrate bondingmethod according to a seventh embodiment of the invention;

[0115]FIG. 16 is a cross-sectional view showing an EL-device substrate324, and a color filter substrate 322 where a liquid hardening resin 333is dropped;

[0116]FIG. 17 is a plan view of the color filter substrate 322 showingthe positions where the resin 333 is dropped;

[0117]FIG. 18 is a cross-sectional view showing a condition in which thecolor filter substrate 322 and the EL device 323 are bonded together;

[0118]FIGS. 19A and 19B are views schematically showing the condition inwhich a surface tension acts in a gap between the substrates being inintimate contact, and a manner in which the inserted resin 333 spreadsdue to a capillary phenomenon;

[0119]FIG. 20 is an enlarged partial cross-sectional view of the colorEL display apparatus 1 according to the third prior art; and

[0120]FIG. 21 is a view schematically showing the process of a bubblebeing formed in the local concave portion P.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0121] Now referring to the drawings, preferred embodiments of theinvention are described below.

[0122]FIG. 1 is a cross-sectional view of a color EL display apparatus31 manufactured by a color EL display apparatus manufacturing methodaccording to a first embodiment of the invention. FIG. 2 is a plan viewof the color EL display apparatus 31. FIGS. 1 and 2 will be describedtogether.

[0123] The color EL display apparatus 31 comprises a main substrate 33,an EL device portion 34, a color filter portion 35, a sealing portion 36and a reinforcing substrate 37. The EL device portion 34 comprises aplurality of lower electrodes 41, a lower insulation layer 42, a lightemission layer 43, an upper insulation layer 44 and a plurality of upperelectrodes 45. The color filter portion 35 comprises one or a pluralityof red filters 47, one or a plurality of green filters 48, one or aplurality of blue filters 49 and a light intercepting filter 50. Thered, green and blue filters 47 to 49 will sometimes be genericallycalled “color filters”. The sealing portion 36 comprises a sealingsubstrate 52 and a protective material layer 53.

[0124] The thickness of the main substrate 53 is a predeterminedreference thickness WC. The reference thickness WC is smaller than thethickness of the substrate where the thin-film EL devices are formed ina typical color EL display apparatus. As described later, the thicknessof the main substrate 33 is larger than the reference thickness WC whenthe EL device portion 34 and the sealing portion 36 are formed, andafter the EL device portion 34 and the sealing portion 36 are formed,the main substrate 33 is processed so as to have the reference thicknessWC.

[0125] The lower electrodes 41 are film strips. The upper electrodes 45are also film strips. All the lower electrodes 41, the lower insulationlayer 42, the light emission layer 43, the upper insulation layer 44 andall the upper electrodes 45 are laminated on one surface 61 of the mainsubstrate 33 in this order from below. The lower electrodes 41 are allarranged in parallel with one another on the one surface 61 of the mainsubstrate 33. The lower electrodes 41 are disposed at intervals of apredetermined width from the adjacent lower electrodes 41. The upperelectrodes are all arranged in parallel with one another on a surface ofthe upper insulation layer 44. The upper electrodes 45 are disposed atintervals of a predetermined width eg from the adjacent upper electrodes45. The direction of length of the lower electrodes 41 and the directionof length of the upper electrodes 45 are perpendicular to each otherwhen viewed from the direction of the normal 62 to the one surface 61 ofthe main substrate 33. That is, the EL device portion 34 has a so-calleddirect matrix structure.

[0126] In the EL device portion 34, the portions where the lowerelectrodes 41 and the upper electrodes 45 intersect when viewed from thedirection of the normal 57 are the thin-film EL devices 63.Consequently, when an alternating field is applied between the lowerelectrodes 41 and the upper electrodes 45, the portion of the lightemission layer 43 that is sandwiched between the lower electrodes 41 andthe upper electrodes 45 emits light. Also, the thin-film EL devices 63are all arranged in a matrix on the one surface 61 of the main substrate33. The thin-film EL devices 63 have the so-called double insulationstructure.

[0127] The color filters 47 to 49 are film strips. The red, green andblue filters 47 to 49 transmit only light beams of the wavelengths ofred, green and blue, respectively. The color filters 47 and 49 transmitlight beams of different wavelengths and have the same configuration.The upper electrodes 45 are each in a one-to-one correspondence with oneof the color filters 47 to 49. The one of the color filters is disposedin a position opposed to the corresponding upper electrode 45 with themain substrate 33 in between within the other surface 64 of the mainsubstrate 33. Consequently, the color filters 47 to 49 are disposed onthe other surface 64 of the main substrate 33 in parallel with oneanother at intervals of a predetermined width fg from the adjacent colorfilters 47 to 49. Also, the direction of length of the color filters 47to 49 is parallel to the direction of length of the upper electrodes 45.The color filters 47 to 49 may be in a one-to-one correspondence withthe lower electrodes 41. In this case, the direction of length of thecolor filters 47 to 49 is parallel to the direction of length of thelower electrodes 41.

[0128] The light intercepting filter 50 covers the portions between thecolor filters 47 to 49 within the other surface 64 of the main substrate33 and the periphery of the color filter being closest to the end of theother surface 64. The light intercepting filter 50 is a so-called blackmask. By the provision of the light intercepting filter 50, the contrastof the color EL display apparatus 31 is superior to that of a color ELdisplay apparatus having no light intercepting filter, and thelegibility is improved.

[0129] The reinforcing substrate 37 is fixed by an adhesive layer 65 tothe other surface 64 of the main substrate 33 with the color filterportion 35 in between. Consequently, the color filter portion 35 issandwiched between the other surface 64 of the main substrate 33 and onesurface 73 of the reinforcing substrate 37.

[0130] One surface 66 of the sealing substrate 52 and the one surface 61of the main substrate 33 are opposed to each other, and the sealingsubstrate 52 and the main substrate 33 are fixed by an adhesive layer73. In the one surface 66 of the sealing substrate 52, a concave portion67 is formed. The inner configuration of the concave portion 67 is asubstantially rectangular parallelepiped. Inside the concave portion 67,lattice-form spacers 69 having slits 68 are left. While the inner spaceof the concave portion 67 is divided into a plurality of parts by thespacers 69, the parts communicate with at least one of the other partsthrough the slits 68. Consequently, the inner space of the concaveportion 67 is continuous. The sealing substrate 52 has a filling hole 70communicating with the inner space of the concave portion 56. Thefilling hole 70 is closed by a sealing member 72 from the other surface71 of the sealing substrate 52.

[0131] The protective material layer 53 is formed by filling aprotective material into the gap between the sealing substrate 52 andthe main substrate 33, that is, the inner space of the concave portion67. The protective material is realized, for example, by a mixture ofsilica gel and silicone oil. The EL device portion 34 is placed in thegap. Consequently, the protective material covers the surface of the ELdevice portion 34. Ends of the lower electrodes 41 and ends of the upperelectrodes 45 are exposed out of the sealing portion 36 as terminals ofthe lower and the upper electrodes 41 and 45.

[0132] Of the above-described parts of the color EL display apparatus31, at least the main substrate 33, the reinforcing substrate 37, thelower electrodes 41 and the lower insulation layer 42 transmit light.The red, blue and green filters 47 to 49 transmit only light beams ofthe wavelengths of red, blue and green, respectively. The lightintercepting filter 50 intercepts light. It is desirable that the upperelectrodes 45 be made of a material having conductivity and beingcapable of reflecting light because the upper electrodes 45 also serveas reflecting plates. When an electric field is created between thelower electrodes 41 and the upper electrode 45, the light emission layer43 emits so-called white light by electroluminescence. Specifically, thelight emission layer 43 is formed by laminating a first light emissionlayer and a second light emission layer. The first light emission layermade of SrS to which Ce is added (SrS:Ce) emits blue-green light byelectroluminescence. The second light emission layer made of ZnS towhich manganese (Mn) is added (ZnS:Mn) emits golden yellow light byelectroluminescence. Consequently, the light emitted from the entirelight emission layer 43 is white light. Consequently, in the color ELdisplay apparatus 31, the other surface 74 of the reinforcing substrate37 is the display screen.

[0133] The method of manufacturing the color EL display apparatus 31will be described below. The main substrate 33 is realized by a glasssubstrate such as OA-2 (manufactured by Nippon Electric Glass Co.,Ltd.). The initial width WD of the main substrate 33 which is largerthan the reference width WC is, for example, 0.7 mm.

[0134] First, a light-transmitting thin film of a conductive material isformed on the one surface 61 of the main substrate 33. The conductivematerial is, for example, ITO (indium-tin oxide), or ZnO to whichaluminum is added (ZnO:Al). The thickness of the thin film is not lessthan 100 nm and not more than 400 nm. As the method of forming the thinfilm, for example, the sputtering method, the electron beam vapordeposition method or the spraying method is used. Then, the thin film ispatterned so as to be striped by so-called photo-etching. Consequently,all the lower electrodes 41 are formed on the one surface 61 of the mainsubstrate 33.

[0135] Then, a light-transmitting thin film made of an insulatingmaterial is formed as the lower insulation layer 42 on the surfaces ofall the lower electrodes 41 and the exposed portion of the one surface61 of the main substrate 33. The insulating material is, for example,SiO₂, SiN, Ta₂O₅ or SrTiO₃. The thickness of the lower insulation layer42 is, for example, not less than 200 nm and not more than 500 nm. Asthe method of forming the insulation layer 42, for example, thesputtering method is used. At least the ends of the lower electrodes 41are not covered with the lower insulation layer 42. The portions of thelower electrodes 41 not being covered with the lower insulation layer 42serve as the terminals of the lower electrodes 41.

[0136] Then, the light emission layer 43 is formed. Specifically, first,the substrate 33 is held at a temperature not less than 450° C. and notmore than 650° C., and film formation by use of the electron beam vapordeposition method is performed with an SrS:CeN pellet as the evaporationsource. Consequently, the first light emission layer is formed on thelower insulation layer 42. The thickness of the first light emissionlayer is, for example, not less than 800 nm and not more than 1500 nm.Then, the substrate 33 is held at a temperature not less than 200° C.and not more than 300° C., and film formation by use of the electronbeam vapor deposition method is performed with a ZnS:Mn pellet as theevaporation source. Consequently, the second light emission layer isformed on the first light emission layer. The thickness of the secondlight emission layer is not less than 200 nm and not more than 500 nm.The SrS:CeN pellet is formed by firing SrS to which CeN of not less than0.05 wt % and not more than 0.3 wt % is added. The ZnS:Mn pellet is ZnSto which Mn of not less than 0.2 wt % and not more than 0.6 wt % isadded. The light emission layer 43 is formed by the above-describedprocess.

[0137] Then, a thin film made of an insulating material is formed on thelight emission layer 43 as the upper insulation layer 44. The thickness,the material and the forming method of the upper insulation layer 44are, for example, the same as those of the lower insulation layer 42.After the formation of the upper insulation layer 44, the substrate 33is heat-treated in a vacuum in order to improve the crystallinity of thelight emission layer 43 formed by the electron beam vapor depositionmethod. The heating temperature of the heat treatment is, for example,not less than 600° C. and not more than 650° C. The heating time of theheat treatment is, for example, not less than one hour and not more thantwo hours.

[0138] Then, a thin film of a conductive material is formed so as tocover the surface of the upper insulation layer 44 and the exposedportion of the one surface 61 of the main substrate 33. The conductivematerial is, for example, aluminum (Al). The thickness of the thin filmis, for example, 100 nm to 500 nm. Then, the thin film is patterned soas to be striped by so-called photo-etching. Consequently, all the upperelectrodes 45 are formed on the upper insulation layer 44. The upperelectrodes 45 extend over the one surface 61 of the substrate 33 beyondends of the upper insulation layer 44. The portions of the upperelectrodes 45 situated on the substrate 33 serve as the terminals of theupper electrodes 45. By the process from the formation of the lowerelectrodes to the formation of the upper electrodes 45, the EL deviceportion 34 is formed on the one surface 61 of the main substrate 33.

[0139] In parallel with the above-described formation of the thin-filmEL devices or following the formation, the one surface 66 of the sealingsubstrate 52 is etched by use of hydrofluoric acid. Consequently, theconcave portion 67 is formed in the surface of the sealing substrate 52.The sealing substrate is made of, for example, glass. The thickness WAof the sealing substrate 52 is, for example, 1.8 mm. The depth of theconcave portion 67 is, for example, 0.7 mm. Then, a filling hole 70 isformed in the sealing substrate 52.

[0140] Then, with the one surface 61 of the main substrate 33 and theone surface 66 of the sealing substrate 52 being opposed to each other,the one surface 61 of the main substrate 33 and the periphery of the onesurface 66 of the sealing substrate 52 are bonded by use of an adhesive.The adhesive which is realized, for example, by epoxy resin becomes theadhesive layer 73 after being hardened. In this case, for example, theterminals of the lower electrodes 41 and the terminals of the upperelectrodes 45 are not opposed to the sealing substrate 52 but areexposed.

[0141] After the bonding of the substrates 33 and 52, air is exhaustedfrom the gap between the main substrate 33 and the sealing substrate 52,that is, the inner space of the concave portion 67, so that the gap isevacuated. Then, the whole of the main substrate 33 with the sealingsubstrate 52 bonded thereto is immersed in a protective material liquidfilled in a bath prepared in a chamber. The protective material liquidis a mixture of silica gel and silicone oil. The weight percentage ofsilica gel in the protective material liquid is 25 wt %. Then, thechamber is filled with nitrogen (N₂). Consequently, the protectivematerial liquid is filled into the gap. After the gap is filled with theprotective material liquid, the filling hole 70 is closed by the sealingmember 72. By the process from the processing of the sealing substrate52 to the closing of the filling hole 70, the sealing portion 36 iscompleted.

[0142] Then, the portion within the outer surface of the main substrate33 other than the other surface 64, and the outer surface of the sealingportion 36 are covered with an etching-resistant resist. The portion is,for example, the portion within the one surface 61 of the main substrate33 where the terminals of the lower and the upper electrodes 41 and 45are formed. Then, the other surface 64 of the main substrate 33 isetched by a wet etching method using an etchant whose main component ishydrofluoric acid until the thickness of the substrate 33 becomes thereference thickness WC. The reference thickness WC is, for example, 75μm.

[0143] After the etching of the main substrate 33, the red filter 47,the green filter 48 and the blue filter 49 are formed byphotolithography so as to be striped, to be in parallel with one anotherand to be spaced on the other surface 64 of the main substrate 33. Then,the light intercepting filter 50 is formed on the other surface 64 ofthe main substrate 33. Consequently, the color filter portion 35 iscompleted. The red filter 47 is realized, for example, by CR-7001manufactured by FUJI-HUNT. The green filter 48 is realized, for example,by CG-7001 manufactured by FUJI-HUNT. The blue filter 49 is realized,for example, by CB-7001 manufactured by FUJI-HUNT. The lightintercepting filter 50 which is a so-called black filter is realized,for example, by CK-7001 manufactured by FUJI-HUNT.

[0144] Lastly, the reinforcing plate 37 is bonded to the other surface64 of the main substrate 33 with the color filter portion 35 in between,for example, by use of a fluid photobond. The photobond becomes theadhesive layer 65 after being hardened. By the above-described process,the color EL display apparatus 31 is completed.

[0145]FIG. 3 is a schematic view of a cross section of a typicaltwo-substrate-bonded-type color EL panel. Since the color EL panel isthe same as the panel disclosed in Japanese Unexamined PatentPublication JP-A 64-40888 (1989) described in the prior art, the samereference numerals as those of FIG. 20 are used and the description ofthe structure thereof is omitted. Since the color filter portion of thispanel has the same structure as the color filter portion 35 of the colorEL display apparatus 31 of FIG. 1, the reference numerals of FIG. 1 areused and the description of the structure thereof is omitted. In FIG. 3,the lower and the upper insulation layers 12 and 14 and the lowerelectrodes 11 are not shown. Between the substrate 3 and thelight-transmitting substrate 4, silicone oil is filled as the protectivematerial.

[0146] The viewing angle of the color EL panel of FIG. 3 willhereinafter be described.

[0147] Generally, when light successively passes through two spacesfilled with media having different refractive indices, Snell's law holdsbetween the angle of incidence of light and the angle of refraction oflight at the interface surface of the two spaces. The light emitted fromthe light emission layer 13 is not refracted at an interface surface 76between the light-transmitting substrate 4 and the protective materiallayer 18 since glass and silicone oil have the same refractive index.Moreover, it is assumed that the light travels in a straight linethrough the upper electrodes 15, the upper insulation layer 14 and thecolor filter portion since the upper electrodes 15, the upper insulationlayer 14 and the color filter portion are sufficiently thinner than thelight-transmitting substrate 4 and the protective material layer 18.Therefore, the light is refracted at the interface surface 77 betweenthe light-transmitting substrate 4 and the air layer only when exitingfrom the inside of the color EL panel into the air.

[0148] The relationship of an expression 1 holds between the angle ofincidence θi of the light emitted from the light emission layer 13 on aninterface surface 77 and the angle of refraction θ of the light at theinterface surface 77. The viewing angle θa of the color EL panel istwice the angle of refraction θ. Therefore, the viewing angle θa isobtained by an expression 2. The viewing angle θa is a screen anglewhere there is no change in tonality. The screen angle is the angle atwhich the user of the color EL panel views the display screen of thecolor EL panel, that is, the interface surface 77 when the user viewsthe display screen. The viewing angle θa is sometimes expressed, when itis assumed that the normal to the interface surface 77 is 0°, by apositive value in the clockwise direction and by a negative value in thecounterclockwise direction with the intersection of the normal and theinterface surface as the center within a virtual plane including thenormal.

[0149] In the expressions shown below, “no” is the refractive index ofair. “ni” is the refractive index of the glass and the silicone oil, andis, for example, 1.5. “fw” is the width of the color filters 47 to 49.“fg” is the width of the interval between adjacent two color filters.The width fg equals the width of the light intercepting filter 50. “pw”is the width of an EL light emission area. The EL light emission area isan area immediately below the upper electrodes 15 in the light emissionlayer 13. The width of the EL light emission area and the width of theupper electrodes 15 are the same. “sg” is the thickness of theprotective material layer 18. The width sg equals the interval betweenthe color filter portion and the upper electrodes 15. “eg” is the widthof the interval between one electrodes of pairs of electrodes of thethin-film EL devices the direction of length of which electrodes isparallel to that of the color filters 47 and 49, that is, the width ofthe interval between two adjacent upper electrodes 15. To maximize theviewing angle θa of the color EL panel, the width fw of the colorfilters 47 to 49 and the width pg of the electrodes are made the same asshown by an expression 3 and the width fg of the intervals between thefilters and the width eg of the intervals between the upper electrodes15 are made the same as shown by an expression 4. $\begin{matrix}{\frac{\sin \quad \theta \quad i}{\sin \quad \theta} = \frac{no}{ni}} & (1) \\\begin{matrix}{{\theta \quad a} = {{\pm \arcsin}\quad \left( {\frac{ni}{no} \times \sin \quad \theta \quad i} \right)}} \\{= {\pm {\arcsin \quad\left\lbrack \frac{\frac{ni}{no} \times \left( {\frac{fw}{2} + {fg} - \frac{pw}{2}} \right)}{\left\{ {\left( {\frac{fw}{2} + {fg} - \frac{pw}{2}} \right)^{2} + ({sg})^{2}} \right\}^{1/2}} \right\rbrack}}}\end{matrix} & (2)\end{matrix}$

fw=pw  (3)

fg=eg  (4)

[0150] The ingredients of the silicone oil are mixed so that therefractive index is substantially the same as the refractive index ofthe substrates 3 and 4. Therefore, by replacing the protective materiallayer 18 by the main substrate 33, replacing the substrate 4 by thereinforcing substrate 37, replacing the color filter portion by thecolor filter portion 35 and replacing the thin-film EL devices 5 by thethin-film EL devices 63, the behavior of the light emitted from thelight emission layer 43 in the color EL display apparatus 31 of thisembodiment can be explained based on the same idea as the behavior ofthe light in the color EL panel of FIG. 3. Therefore, theafter-processing thickness of the main substrate 33, that is, thereference thickness WC will be described based on the expressions (2) to(4).

[0151] When the viewing angle θa is decided, the relationship betweenthe width fg of the intervals between the color filters 47 to 49 and thethickness sg of the protective material 18 is found based on theexpression 2. When it is assumed that the width fg of the intervalsbetween the color filters 47 to 49 and the width eg of the intervalsbetween the upper electrodes 15 are the same as shown by the expression4, the relationship between the width eg of the intervals between theupper electrodes 15 and the thickness sg of the protective materiallayer 18 is found based on the expression 2. Table 1 shows therelationship between the width eg of the intervals between the upperelectrodes 15 and the thickness sg of the protective material layer 18when the viewing angle θa is 160° (±80°). Table 2 shows the relationshipbetween the width eg of the intervals between the upper electrodes 15and the thickness sg of the protective material layer 18 when theviewing angle θa is 80° (±40°). The viewing angle of 160° is required,for example, when the color EL display apparatus 31 is used in aso-called wide viewing angle mode. The viewing angle of 80° is required,for example, when the color EL display apparatus 31 is used as a displayscreen of a personal computer for private use. TABLE 1 Width ofintervals Thickness of protective between electrodes (μm) material layer(μm)  25  30  50  60 100 120 150 180 200 240 250 300

[0152] TABLE 2 Width of intervals Thickness of protective betweenelectrodes (μm) material layer (μm)  25  55  50 110 100 220 150 330 200440 250 550

[0153] When the above-mentioned idea in the color EL panel is applied tothe color EL display apparatus 31 of this embodiment, the thickness sgof the protective material layer 18 corresponds to the after-processingthickness of the main substrate 33, that is, the reference thickness WC.Therefore, when the viewing angle required by the color EL displayapparatus 31 is decided, the width of the interval between oneelectrodes of pairs of electrodes 41 and 45 of the thin-film EL devices63 the direction of length of which electrodes is parallel to the colorfilters 47 and 49, that is, the width eg of the intervals between theupper electrodes 45 is a factor that decides the reference thickness WC.From the tables, it is apparent that when the width eg of the intervalsbetween the upper electrodes 45 is the same, the wider the viewing angleis, the smaller the thickness sg of the protective material layer 18 is.Therefore, in order that the viewing angle is not less than 160°, it isnecessary that the reference thickness WC be not more than 1.2 times thewidth eg of the intervals between the electrodes.

[0154] The color EL display apparatus 31 has the so-called direct matrixstructure. That is, a plurality of strip-form lower and upper electrodes41 and 45 alternately intersect to form a so-called XY matrix. Theelectrode pitch pp of the upper electrodes 45 is the sum of the width pwof the upper electrodes 45 and the width eg of the intervals between theupper electrodes 45. For example, in a currently-used typical EL panel,when the electrode pitch pp is 0.3 mm (300 μm), the width pw of theupper electrodes 45 is 210 μm and the width eg of the intervals betweenthe upper electrodes 45 is 90 μm.

[0155] When the component ratio between the width pw of the upperelectrodes 45 and the width eg of the intervals between the upperelectrodes 45 is decided, the fill factor of the color EL displayapparatus 31 is also decided. For example, when the electrode pitch ppis 0.3 mm, the width pw of the upper electrodes 45 is 210 μm and thewidth eg of the intervals between the upper electrodes 45 is 90 μm, itis found from the expression (5) that the fill factor is 0.49. The fillfactor influences the panel screen brightness of the EL panel, that is,the brightness of the display screen of the color EL display apparatus31. For example, it is found from the expression (6) that the panelscreen brightness of an EL panel using EL devices having a lightemission brightness characteristic of 100 cd/m^(2 is) 49 cd/m².

(210÷300)×210÷300=0.49  (5)

100[cd/m ²]×0.49=49 [cd/m ²]  (6)

[0156] Therefore, in order to improve the panel screen brightness of thecolor EL display apparatus 31, it is necessary to maximize the fillfactor. Consequently, it is desired to minimize the width eg of theintervals between the upper electrodes 45. Considering typical uses ofthe color EL panel, the color EL display apparatus 1 is required toprovide display of as high resolution as possible. Consequently, theelectrode pitch pp of the color EL display apparatus 31 is frequentlyset to not less than 0 and not more than 0.5 mm. In this case, furtherconsidering the fill factor, the width eg of the intervals between theupper electrodes 45 is set to approximately not less than 50 μm and notmore than 150 μm. When the electrode pitch pp and the width eg of theintervals between the upper electrodes 45 are decided as mentionedabove, in order that the viewing angle θa of the color EL displayapparatus 31 is wide, that is, not less than 160°, it is necessary thatthe after-processing thickness of the main substrate 33 be not more than180 μm. The thinner the main substrate 33 is, the higher the possibilityis that the main substrate 33 breaks at a portion of after processing ofthe main substrate 33 in the manufacturing process of the color ELdisplay apparatus 31. Considering the processing accuracy in theprocessing of the main substrate 33, an error of ±10 μm from thereference thickness WC is caused in the after-processing thickness ofthe main substrate 33. For this reason, when the reference thickness isless than 25 μm, there is no margin. From the above, theoretically, itis desirable that the reference thickness WC be not less than 25 μm andnot more than 200 μm.

[0157] In actual EL panels, as shown in FIG. 3, the width fw of thecolor filters 47 to 49 is frequently larger than the width pw of theupper electrodes 45, and the width fg of the intervals between the colorfilters 47 to 49 is frequently smaller than the width eg of theintervals between the upper electrodes 45. Since the width eg betweenthe intervals of the electrodes is smaller than that in theabove-described example for this reason, it is desired that thereference thickness WC of the main substrate 33 be smaller than theabove-mentioned theoretical thickness. Further, in the method ofmanufacturing the color EL display apparatus 31 according to thisembodiment, a chemical etching method using an etchant of hydrofluoricacid is used as the method of thinning the main substrate 33. In thecase where the chemical etching method is used, an etching error ofapproximately ±10 μm is caused even when the etching conditions are heldoptimum. From these, although it is desired from the viewpoint of theviewing angle that the after-processing thickness of the main substrate33 be as small as possible, from the viewpoint of handling of thesubstrate after the processing, it is necessary that theafter-processing thickness be at least approximately 50 μm as thepractical design level. Moreover, considering the electrode pitch of thecurrently-used EL panel, in order to obtain the viewing angle of 80°, itis necessary that the after-processing thickness of the main substrate33 be not more than 100 μm. From the above, it is desired that thereference thickness WC of the main substrate 33 be not less than 50 μmand not more than 100 μm from a practical point of view.

[0158] The initial thickness WD of the main substrate 33 and thethickness WA of the sealing substrate 52 will hereinafter be described.

[0159] The EL display portion 34 has a structure such that the lower andthe upper electrodes 41 and 45, the lower and the upper insulationlayers 42 and 44 and the light emission layer 43 are laminated.Consequently, a multiplicity of thin film pieces are laminated on themain substrate 33. Stress exists inside each of the film pieces.Therefore, as the main substrate 33 is thinned, the main substrate 33warps in accordance with the stress inside the film pieces. Since theinternal stress acts in a direction that extends the film pieces in manycases, the main substrate 33 frequently warps in a direction thatconvexes the surfaces of the films.

[0160] In order to examine the relationship between the thickness of themain substrate 33 and the warp of the main substrate 33, a color ELdisplay apparatus having a first glass substrate with an initialthickness of 0.5 mm as the main substrate 33 and a color EL displayapparatus having a second glass substrate with an initial thickness of0.7 mm as the main substrate 33 were produced by the above-describedmethod. The warp of the main substrate 33 was greater in the case wherethe first glass substrate was used as the main substrate 33 than in thecase where the second glass substrate was used as the main substrate 33.In the case where the first glass substrate was used as the mainsubstrate 33, it was difficult to bond the sealing substrate 52 and themain substrate 33 because the warp of the main substrate 33 was great.However, in the case where the second glass substrate was used as themain substrate 33, the warp of the main substrate 33 was small and itwas possible to bond the sealing substrate 52 and the main substrate 33.Therefore, it is found that in order to suppress the warp of the mainsubstrate 33 due to the internal stress existing inside the EL deviceportion 34, it is necessary that the initial thickness WD of the mainsubstrate 33 be not less than 0.7 mm.

[0161] For this reason, it is desirable that the initial thickness WD ofthe main substrate 33 be not less than 0.7 mm. From the viewpoint ofsuppression of the warp of the main substrate 33, there is no specificupper limit to the initial thickness WD of the main substrate 33.However, considering the easiness of handling of the main substrate 33,it is preferable that the initial thickness WD of the main substrate 33be as small as possible. Therefore, it is most desirable that theinitial thickness WD of the main substrate 33 be not less than 0.7 mmand as close to 0.7 mm as possible.

[0162] In the manufacturing process of this embodiment, after theformation of the EL device portion 34, the main substrate 33 isprocessed to a thickness of less than 0.1 mm. The sealing substrate 52is bonded to the main substrate 33 before the processing of the mainsubstrate 33, and suppresses the warp of the main substrate 33 after theprocessing of the main substrate 33. For this reason, the main substrate33 does not warp when the main substrate 33 is 0.7 mm in thickness afterthe processing. Since the concave portion 67 is formed in the sealingsubstrate 52 to create a gap to be filled with the protective materialliquid, it is necessary to decide the thickness of the sealing substrate52 in consideration of the concave portion 67 in addition to thematerial of the sealing substrate 52. As mentioned in theabove-described manufacturing method, in the case where the sealingsubstrate 52 is realized by a glass substrate, considering the glassstrength, it is desirable that the thickness WA of the sealing substrate52 be not less than 0.8 mm. From the viewpoint of suppression of thewarp of the main substrate 33, there is no specific upper limit to thethickness WA of the sealing substrate 52. However, considering theeasiness of handling, it is preferable that the initial thickness WD ofthe main substrate 33 be as small as possible. Therefore, it is mostdesirable that the thickness WA of the sealing substrate 52 be not lessthan 0.8 mm and as close to 0.8 mm as possible.

[0163] The thickness WB of the reinforcing substrate 37 will hereinafterbe described. The above-described color EL display apparatus 34 isfrequently formed into a unit. For this reason, for example, a drivingIC is further attached to the color EL display apparatus 34 and thecolor EL display apparatus 31 is fixed to a frame for display. Thereinforcing substrate 37 is indispensable, for example, when the tab ofthe driving IC is connected to the terminals of the lower and the upperelectrodes 41 and 45 and when the color EL display apparatus 31 is fixedto the frame in the process of forming the EL display apparatus 34 intoa unit. In the case where the reinforcing substrate 37 is realized by aglass substrate, it is desirable that the thickness WB of thereinforcing substrate 37 be not less than 0.5 mm in order to facilitatethe handling of the color EL display apparatus 31 when performing theabove-mentioned connection and fixing. From the viewpoint offacilitation of the handling, there is no specific upper limit to thethickness WB of the reinforcing substrate 37. However, from a practicalpoint of view, it is preferable that the thickness WB of the reinforcingsubstrate 52 be as thin as possible. Therefore, it is desirable that thethickness WB of the reinforcing substrate 37 be not less than 0.5 mm andas close to 0.5 mm as possible.

[0164] The color EL display apparatus 31 manufactured by theabove-described method has a seal life and a mechanical strengthsufficient for practical use and has a viewing angle wide enough forpractical use compared to prior art color EL display apparatuses.Further, the legibility of the color EL display apparatus 31 is highcompared to those of prior art color EL display apparatuses. From these,the color EL display apparatus 31 can be used as display devices forvarious uses.

[0165] Moreover, the structure of the inactivation protecting means ofthe thin-film EL devices 63, that is, the sealing portion 36 issubstantially the same as the structure of the sealing portion used forthe currently-used EL display apparatuses described in the prior art.Therefore, the color EL display apparatus 31 can obtain a seal lifesufficient for practical use and can ensure a long-term reliabilitysufficient for practical use. Further, between the thin-film EL devices63 and the color filters 47 to 49, the main substrate 33 is interposedand the protective material layer 53 is not interposed. Consequently,blur and distortion due to silica gel in the protective material layer53 can be prevented from being caused in images displayed on the displayscreen of the color EL display apparatus 31.

[0166] From these, by using the above-described manufacturing method,the color EL display apparatus 31 capable of ensuring a long-termreliability sufficient for practical use and maintaining more excellentdisplay quality than prior art color EL display apparatuses can easilybe manufactured. The above-described manufacturing method can also beused for the manufacture of a color EL display apparatus employingorganic EL devices which deteriorate due to moisture, and in this case,the above-mentioned effects can also be obtained.

[0167]FIG. 4 is a cross-sectional view of a color EL display apparatus91 manufactured by a color EL display apparatus manufacturing methodaccording to a second embodiment of the invention. FIG. 5 is a plan viewof the color EL display apparatus 91. FIGS. 4 and 5 will be describedtogether. The color EL display apparatus 91 of the second embodiment isthe same as the color EL display apparatus 31 of the first embodimentexcept the subsequently-described points associated with the sealingportion. Therefore, parts whose structures and operations are the sameas those of parts of the color EL display apparatus 31 are denoted bythe same reference numerals. Of the descriptions of the color EL displayapparatus 91, the same descriptions as those of the first embodiment areomitted.

[0168] The color EL display apparatus 91 comprises the main substrate33, the EL device portion 34, the color filter portion 35, a sealingportion 93 and the reinforcing substrate 37. The sealing portion 93comprises a sealing substrate 94 and a protective material layer 95. Theinitial thickness WD of the main substrate 33, the reference thicknessWC and the thickness WB of the reinforcing substrate 37 are decidedbased on the idea described in the first embodiment.

[0169] One surface 97 of the sealing substrate 94 and the one surface 61of the main substrate 33 are opposed, and the sealing substrate 94 isfixed to the main substrate 33 by the adhesive layer 73. In the onesurface 97 of the sealing substrate 94, a concave portion 98 is formed.The inner configuration of the concave portion 98 is a substantiallyrectangular parallelepiped. The sealing substrate 94 has the fillinghole 70 communicating with the inner space of the concave portion 98.The filling hole 70 is closed by the sealing member 72 from the othersurface 99 of the sealing substrate 94. The thickness WA of the sealingsubstrate 94 is decided based on the same idea as that of the sealingsubstrate 52 of the first embodiment. It is desirable that the thicknessWA be not less than 0.8 mm.

[0170] The protective material layer 95 is formed by filling aprotective material into the gap between the sealing substrate 94 andthe main substrate 33, that is, the inner space of the concave portion98. The protective material is realized, for example, by a mixture ofsilica gel and silicone oil. The EL device portion 34 is placed in thegap. Consequently, the protective material covers the surface of the ELdevice portion 34. The ends of the lower electrodes 41 and the ends ofthe upper electrodes 45 are exposed out of the sealing portion 93 as theterminals of the lower and the upper electrodes 41 and 45.

[0171] The method of manufacturing the color EL display apparatus 91will hereinafter be described. Of the descriptions of steps of themethod of manufacturing the color EL display apparatus 91 according tothe second embodiment, the descriptions of the same steps as those ofthe method of manufacturing the color EL display apparatus 31 accordingto the first embodiment are omitted.

[0172] The main substrate 33 is realized by a glass substrate such asOA-2 (manufactured by Nippon Electric Glass Co., Ltd.) The initial widthWD of the main substrate 33 is larger than the reference width WC.First, the EL device portion 34 is formed on the one surface 61 of themain substrate 33. The step of forming the EL device portion 34 is thesame as the step of forming the EL device portion 34 in the method ofmanufacturing the color EL display apparatus 31 according to the firstembodiment.

[0173] In parallel with the above-described formation of the EL deviceportion 34 or following the formation, digging processing using agrindstone or a sandblast is performed on the one surface 97 of thesealing substrate 94. Consequently, the concave portion 98 is formed inthe one surface 97 of the sealing substrate 94. The sealing substrate 94is made of, for example, glass. The thickness WA of the sealingsubstrate 94 is, for example, 1.1 mm. The depth of the concave portion98 is, for example, 0.4 mm. The periphery of the one surface 97 of thesealing substrate 94 is left after the digging processing as a bondingframe for bonding the sealing substrate 94 to the main substrate 33.Then, the filling hole 70 is formed in the sealing substrate 94.

[0174] Then, with the one surface 61 of the main substrate 33 and theone surface 97 of the sealing substrate 94 being opposed to each other,the one surface 61 of the main substrate 33 and the periphery of the onesurface 97 of the sealing substrate 94 are bonded by an adhesive. Theadhesive which is realized, for example, by epoxy resin becomes theadhesive layer 73 after being hardened. The terminals of the lowerelectrodes 41 and the terminals of the upper electrodes 45 are notopposed to the sealing substrate 94 but are exposed.

[0175] After the bonding of the substrates 33 and 94, the protectivematerial liquid is filled into the gap between the main substrate 33 andthe sealing substrate 94, that is, the inner space of the concaveportion 98 through the filling hole 70. The step of filling theprotective material liquid is the same as the protective material liquidfilling step of the method of manufacturing the color EL displayapparatus 31 according to the first embodiment. The weight percentage ofsilica gel in the protective material liquid is 30 wt %. After the gapis filled with the protective material liquid, the filling hole 70 isclosed by the sealing member 72. By the process from the processing ofthe sealing substrate 94 to the closing of the filling hole 70, thesealing portion 93 is completed.

[0176] Then, the portion within the outer surface of the main substrate33 other than the other surface 64, and the outer surface of the sealingportion 36 are covered with rubber or the like. The portion is, forexample, the portion within the one surface 61 of the main substrate 33where the terminals of the lower and the upper electrodes 41 and 45 areformed. Then, the other surface 64 of the main substrate 33 isstepwisely ground by a glass grinder until the thickness of the mainsubstrate 33 becomes the reference thickness WC. The reference thicknessWC is, for example, 75 μm.

[0177] In parallel with the above-described formation of the EL deviceportion 34 and the sealing portion 93 or following the formation, thecolor filter portion 35 is formed on one surface of the reinforcingsubstrate 37. The step of forming the color filter portion 35 is thesame as the step of forming the color filter portion 35 in the method ofmanufacturing the color EL display apparatus 31 according to the firstembodiment except that the surface where the color filter portion 35 isformed is changed from the other surface 64 of the main substrate 33 tothe one surface 73 of the reinforcing substrate 37.

[0178] Lastly, the reinforcing substrate 37 is bonded to the othersurface 64 of the main substrate 33, for example, by use of a fluidphotobond. In this case, the one surface 73 of the reinforcing substrate37 and the other surface 64 of the main substrate 33 are opposed to eachother and the color filter portion 35 is interposed therebetween. Thephotobond becomes the adhesive layer 65 after being hardened. By theabove-described process, the color EL display apparatus 91 is completed.

[0179] The main substrate 33 and the sealing substrate 94 can beprocessed by grinding as well as chemical etching described in the firstembodiment. The color EL display apparatus 91 manufactured by theabove-described method has a seal life and a mechanical strengthsufficient for practical use and has a viewing angle wide enough forpractical use compared to prior art color EL display apparatuses.Further, by the provision of the light intercepting filter 50, thecontrast of the color EL display apparatus 91 is superior to that of acolor EL display apparatus having no light intercepting filter, and thelegibility is improved. Therefore, the legibility of the color ELdisplay apparatus 91 is higher than those of prior art color EL displayapparatuses. From these, the color EL display apparatus 91 can be usedas display devices for various uses. Moreover, by using theabove-described manufacturing method, the color EL display apparatus 91capable of ensuring a long-term reliability sufficient for practical useand maintaining more excellent display quality than prior art color ELdisplay apparatuses can easily be manufactured.

[0180]FIG. 6 is a cross-sectional view of a color EL display apparatus111 manufactured by a color EL display apparatus manufacturing methodaccording to a third embodiment of the invention. FIG. 7 is a plan viewof the color EL display apparatus 111. FIGS. 6 and 7 will be describedtogether. The color EL display apparatus 111 of the third embodiment isthe same as the color EL display apparatus 91 of the second embodimentexcept the subsequently-described points associated with the mainsubstrate and the reinforcing substrate. Therefore, parts whosestructures and operations are the same as those of parts of the color ELdisplay apparatuses 31 and 91 are denoted by the same referencenumerals. Of the descriptions of the color EL display apparatus 111, thesame descriptions as those of the first embodiment are omitted.

[0181] The color EL display apparatus 111 comprises a main substrate113, the EL device portion 34, the color filter portion 35, the sealingportion 93 and a reinforcing substrate 114. The EL device portion 34 isdisposed on one surface 116 of the main substrate 113. In the othersurface 117 of the main substrate 113, a concave portion 118 is formed.The inner configuration of the concave portion 118 is a substantiallyrectangular parallelepiped. The distance between the bottom surface ofthe concave portion 118 and the one surface 116 of the main substrate113 is the reference thickness WC. The periphery of the main substrate113 is held at the initial thickness WD of the main substrate 113 and isthicker than the reference thickness WD. The color filter portion 35 isdisposed on the bottom surface of the concave portion 118.

[0182] The reinforcing substrate 114 which is smaller than the innerspace of the concave portion 118 of the main substrate 33 can be placedin the concave portion 118. The reinforcing substrate 114 is fixed tothe bottom surface of the concave portion 118 of the main substrate 113by the adhesive layer 65. A resin layer 119 is interposed between aninner peripheral surface 121 of the concave portion 118 and the sidesurfaces of the reinforcing substrate 114. Viewed from the direction ofthe normal 122 to the one surface 116 of the main substrate 113, theinner peripheral surface 121 of the concave portion 118 substantiallycoincides with the center 124 of a periphery 123 of the sealingsubstrate 95, that is, the center of the bonding frame of the sealingsubstrate 94. The initial thickness WD of the main substrate 113, thereference thickness WC of the main substrate 113 and the thickness WB ofthe reinforcing substrate 114 are decided based on the idea the same asthe initial thickness WD of the main substrate 33, the referencethickness WC of the main substrate 33 and the thickness WB of thereinforcing substrate 37 of the first embodiment.

[0183] The method of manufacturing the color EL display apparatus 111will hereinafter be described. Of the descriptions of steps of themethod of manufacturing the color EL display apparatus 111 according tothe third embodiment, the descriptions of the same steps as those of themethod of manufacturing the color EL display apparatuses 31 and 91according to the first and the second embodiments are omitted.

[0184] The main substrate 113 is realized by a glass substrate such asOA-2 (manufactured by Nippon Electric Glass Co., Ltd.). The initialwidth WD of the main substrate 113 is larger than the referencethickness WC. First, the EL device portion 34 is formed on the onesurface 116 of the main substrate 113. The step of forming the EL deviceportion 34 is the same as the step of forming the EL device portion 34in the method of manufacturing the color EL display apparatus 31according to the first embodiment.

[0185] In parallel with the above-described formation of the thin-filmEL devices or following the formation, the one surface 97 of the sealingsubstrate 94 is etched by use of hydrofluoric acid. Consequently, theconcave portion 98 is formed in the one surface 97 of the sealingsubstrate 94. The sealing substrate is made of, for example, glass. Thethickness WA of the sealing substrate 94 is, for example, 1.1 mm. Thedepth of the concave portion 98 is, for example, 0.4 mm. The periphery123 of the one surface 97 of the sealing substrate 94 is left after thedigging processing as a bonding frame for bonding the sealing substrate94 to the main substrate 113. Then, the filling hole 70 is formed in thesealing substrate 94.

[0186] Then, with the one surface 116 of the main substrate 113 and theone surface 97 of the sealing substrate 94 being opposed to each other,the one surface 116 of the main substrate 113 and the periphery of theone surface 97 of the sealing substrate 94 are bonded by use of anadhesive. The adhesive which is realized, for example, by epoxy resinbecomes the adhesive layer 73 after being hardened. In this case, forexample, the terminals of the lower electrodes 41 and the terminals ofthe upper electrodes 45 are not opposed to the sealing substrate 94 butare exposed.

[0187] After the bonding of the substrates 113 and 94, the protectivematerial liquid is filled into the gap between the main substrate 113and the sealing substrate 94, that is, the inner space of the concaveportion 98 through the filling hole 70. The step of filling theprotective material liquid is the same as the protective material liquidfilling step of the method of manufacturing the color EL displayapparatus 31 according to the first embodiment. The weight percentage ofsilica gel in the protective material liquid is 25 wt %. After the gapis filled with the protective material liquid, the filling hole 70 isclosed by the sealing member 72. By the process from the processing ofthe sealing substrate 94 to the closing of the filling hole 70, thesealing portion 93 is completed.

[0188] Then, the outer surface of the sealing portion 93, the portionwithin the one surface 116 of the main substrate 113 where the terminalsof the lower and the upper electrodes 41 and 45 are formed, and aperiphery 125 of the other surface 117 of the main substrate 113 arecovered with an etching-resistant resist, a PET film or the like. Theperiphery 125 of the other surface 117 of the main substrate 113 is, forexample, a frame-shaped portion within the other surface 117 from theend of the other surface 117 to the portion coinciding with the center124 of the periphery of the sealing substrate 94 when viewed from thedirection of the normal 122. Then, the other surface 117 of the mainsubstrate 113 is etched by a wet etching method using an etchant whosemain component is hydrofluoric acid. Consequently, the concave portion118 is formed in the other surface 117 of the main substrate 113. Thedistance between the bottom surface of the concave portion 118 of themain substrate 113 and the one surface 116 of the main substrate 113 isthe reference thickness WC. The reference thickness WC is, for example,75 μm. The peripheral portion 125 of the other surface 117 of the mainsubstrate 113 is left in the frame shape after the digging processing.

[0189] In parallel with the above-described formation of the sealingportion 93 and the processing of the main substrate 113 or following theformation and the processing, the color filter portion 35 is formed onone surface 126 of the reinforcing substrate 114. The step of formingthe color filter portion 35 is the same as the step of forming the colorfilter portion 35 in the method of manufacturing the color EL displayapparatus 91 according to the second embodiment except that thereinforcing substrate 37 is replaced by the reinforcing substrate 114.

[0190] Then, the reinforcing substrate 114 is bonded to the bottomsurface of the concave portion 118 of the main substrate 113, forexample, by use of a fluid photobond. In this case, the one surface 126of the reinforcing substrate 114 and the bottom surface of the concaveportion 118 of the main substrate 33 are opposed to each other and thecolor filter portion 35 is interposed therebetween. The photobondbecomes the adhesive layer 65 after being hardened. Lastly, for example,epoxy resin is filled into the gap between the inner peripheral surface121 of the concave portion 118 of the main substrate 113 and the sidesurfaces of the reinforcing substrate 114 in order to reinforce the mainsubstrate 113. The epoxy resin becomes the resin layer 119 after beinghardened. By the above-described process, the color EL display apparatus111 is completed.

[0191] The color EL display apparatus 111 manufactured by theabove-described method has a seal life and a mechanical strengthsufficient for practical use and has a viewing angle wide enough forpractical use compared to prior art color EL display apparatuses.Further, by the provision of the light intercepting filter 50, thecontrast of the color EL display apparatus 111 is superior to that of acolor EL display apparatus having no light intercepting filter, and thelegibility is improved. Therefore, the legibility of the color ELdisplay apparatus 111 is higher than those of prior art color EL displayapparatuses. From these, the color EL display apparatus 111 can be usedas display devices for various uses. Moreover, by using theabove-described manufacturing method, the color EL display apparatus 111capable of ensuring a long-term reliability sufficient for practical useand maintaining more excellent display quality than prior art color ELdisplay apparatuses can easily be manufactured.

[0192] Further, the reinforcing substrate 114 is bonded to the peripherywithin the main substrate 113, that is, the thick portion of the mainsubstrate 113 by the resin layer 119. For this reason, the mechanicalstrength of the color EL display apparatus 111 is greater than those ofthe color EL display apparatuses 31 and 91 of the first and the secondembodiments. When the color EL display apparatus 111 of the thirdembodiment is formed into a unit, the tab of the driving IC can directlybe connected to the terminals of the upper and the lower electrodes 45and 41 on the main substrate 113. In the above-mentioned case, further,the color EL display apparatus 111 can directly be fixed to the framefor display. Consequently, it is facilitated to form the color ELdisplay apparatus 111 into a unit.

[0193]FIG. 8 is a cross-sectional view showing a color EL displayapparatus 220 manufactured by a color EL display apparatus manufacturingmethod according to a fourth embodiment of the invention. The color ELdisplay apparatus 220 comprises an EL device 221 and a color filtersubstrate 222 bonded together. The EL device 221 comprises alight-transmitting EL-device substrate 224, an EL device portion 223 anda sealing portion 225. The color filter substrate 222 comprises alight-transmitting substrate 231 and a color filter 232.

[0194] The EL device 221 is a double-insulation-type thin-film EL devicein which a first electrode 226, a first insulation film 227, a lightemission layer 228, a second insulation film 229 and a second electrode230 constituting the EL device portion 223 are successively laminated onthe EL-device substrate 224 made of glass. To form the first electrode226, ITO (indium-tin oxide) is deposited on one surface 224 a of theEL-device substrate 224 in a thickness of approximately 100 nm by theelectron beam vapor deposition method or the high-frequency sputteringmethod, and the first electrode 26 is formed in stripes by wet etchingusing a photoresist.

[0195] The first insulation film 227 laminated on the first electrode226 comprises a lamination of an SiO₂ film with a thickness ofapproximately 40 nm and an Si₃N₄ film with a thickness of approximately220 nm, and is formed by the high-frequency sputtering method. As thelight emission layer 228 laminated on the first insulation film 227, aZnS:Mn layer is formed in a thickness of approximately 7000 Å by theelectron beam vapor deposition method using Zn:Mn as the evaporationsource. The EL light emission layer 228 emits yellow light including redto green light emission ranges by applying an alternating field betweenthe first and the second electrodes 226 and 230, and by dividing thelight into spectra by red and green color filters, a multicolor ELdisplay apparatus of red and green can be produced. The reason why sucha light emission layer 228 is used in this embodiment is that amonochrome EL display apparatus using such a light emission layer hasalready been put to practical use and it has been confirmed that thematerial of the light emission layer is excellent in light emissionbrightness and light emission stability. The color EL display apparatusembodying the invention is not limited to such a multicolor EL displayapparatus of red and green, but a full-color EL display apparatus can beproduced, for example, by dividing into spectra white EL light emittedfrom a lamination of ZnS:Mn and SrS:Ce light emission layers by colorfilters of red, green and blue.

[0196] The second insulation film 229 laminated on the light emissionlayer 228 comprises, for example, a lamination of an Si₃N₄ film with athickness of approximately 100 nm and an SiO₂ film with a thickness ofapproximately 35 nm. These films are formed by the high-frequencysputtering method. After the formation of the second insulation film229, high vacuum annealing is performed in order to improve thecrystallinity of the light emission layer 228. The high vacuum annealingis performed at 630° C. in a high vacuum of not more than 1×10⁻⁴ Pa.

[0197] Lastly, as the second electrode 230, Al is deposited in athickness of approximately 500 nm by heat vapor deposition, and thesecond electrode 230 is formed in stripes perpendicular to the firstelectrode 226 by wet etching using a photoresist, so that the EL deviceportion 223 is completed.

[0198] To form the moistureproof sealing portion 225 of the EL device221, a protective glass 242 where digging processing is performed to adepth T1 of approximately 1 mm is disposed so that the EL device portion223 is sealed in the portion where the digging processing is performed,and the periphery of the protective glass 242 is bonded onto the onesurface 224 a of the EL-device substrate 224 by use of an epoxy resin238. Then, silicone oil mixed with silica gel is filled into a sealedspace 237 where the EL device portion 223 is sealed through an oilintroduction hole 235 formed in the protective glass 242 in advance, andthe introduction hole is closed by a sealing glass 236. In the casewhere silicone oil is filled, under a condition where the sealed space237 is evacuated by exhausting air in the sealed space 237 through theoil introduction hole 235, silicone oil is absorbed through the oilintroduction hole 235 so that the sealed space 237 is filled withsilicone oil. Thus, since it is necessary that the sealed space 237 beevacuated when oil is filled, the EL-device substrate 224 has athickness that endures such a vacuum when oil is filled.

[0199] After the EL device portion 223 and the moistureproof sealingportion 225 are formed on the EL-device substrate 224, by etching usinghydrofluoric acid, a concave portion 244 is formed in the EL-devicesubstrate 224 on the side opposite to the side where the EL deviceportion 223 is provided so that the thickness T2 of the portion of theEL-device substrate 224 opposed to the EL device portion 223 isapproximately 100 μm. At this time, in view of the mounting of the colorfilter substrate 222, only the portion where the color filter substrate222 is fitted is etched into a concave so that the periphery of theEL-device substrate 224 is left in a frame shape. By thus forming theconcave portion 244 in the EL-device substrate 224, the EL device 221and the color filter substrate 222 are bonded together with the colorfilter substrate 222 being fitted in the concave portion of theEL-device substrate 224, so that the bonding strength increases. As aresult, the color EL display apparatus 220 has a sufficient mechanicalstrength. Moreover, since the EL-device substrate 224 interposed betweenthe EL device portion 223 and the color filter 232 is thinned byetching, the distance between the first electrode 226 of the EL deviceportion 223 and the color filter 232 decreases. Consequently, theviewing angle deterioration due to color displacements can be prevented,so that a large viewing angle can be ensured.

[0200] The methods of mounting the color filter 232 include thefollowing: a method in which the color filter 232 is directly formed onthe other surface 224 b which is the bottom surface of the concaveportion 244 of the EL-device substrate 224, and the substrate 231 isbonded thereonto; and a method in which the substrate 231 where thecolor filter 232 is formed is bonded to the other surface 224 b of theEL-device substrate 224. According to the latter method, since anadhesive layer is interposed between the color filter 232 and theEL-device substrate 224, the thickness of the adhesive layer affects theviewing angle. According to the former method, it is necessary todirectly form the color filter 232 on the other surface 224 b of theEL-device substrate 224 which is the bottom surface of the concaveportion 244, and the production of the color filter 232 is difficult.Therefore, this embodiment employs the latter method where theproduction of the color filter 232 is easier.

[0201] The color filter 232 of the color filter substrate 222 comprisesred and green filters R and G alternately arranged on one surface 231 aof a light-transmitting glass substrate. Black filters Bk are formedbetween the filters R and G. The color filter substrate 222 and theEL-device substrate 224 of the EL device 221 are bonded together byfilling a thermosetting synthetic resin 233 into the gap between thecolor filter 232 side surface of the color filter substrate 222, thatis, the surfaces of the filters R, G and BK opposed to the other surface224 b of the EL-device substrate 224 and the one surface 231 a of thesubstrate 231, and the other surface 224 b of the EL-device substrate224. The one surface 231 a of the substrate 231 where the color filter232 is not disposed and the EL-device substrate 224 are fixed at notless than two points (at both ends of the substrate 231 in FIG. 8) by aphoto-setting resin 240. The gap between the color filter substrate 222and the EL-device substrate 224 is filled with a silicone resin 241.Thus, the color filter substrate 222 and the EL device 221 are bondedtogether with a great strength.

[0202] Subsequently, the general outline of the method of bonding the ELdevice 221 and the color filter substrate 222 will be shown. First, asshown in FIG. 9, the color filter substrate 222 and the EL device 221are prepared, and onto the other surface 224 b of the EL-devicesubstrate 224 of the EL device 221, a thermosetting resin 233 such as FASealer 1017C (product name) is dropped so as to convexly bulge in aconical shape having one convex portion as shown in FIG. 9. Thethermosetting resin 233 has no bubbles mixed therein, and has aviscosity of a degree such that the thermosetting resin does not thinlyspread but convexly bulges when dropped as mentioned above. To satisfythis condition, the thermosetting resin 233 of this embodiment has aviscosity of approximately 1500 to 3000 cps at an ordinary temperatureof 25° C. On the color filter substrate 222, the photo-setting resin 240is placed on at least two points of the portion of the one surface 231 aof the substrate 231 where the color filter 232 is not disposed.

[0203] Then, as shown in FIG. 10, the EL device 221 and the color filtersubstrate 222 are brought into intimate contact with each other by anintimate contact jig 246. The intimate contact jig 246 having an ELsubstrate support 245 and a pressing member 247 first places the ELdevice 221 on the EL substrate support 245 so that the other surface 224b of the EL-device substrate 224 faces upward, then, places the colorfilter substrate 222 on the EL device 221 so that the color filter 232of the color filter substrate 222 is opposed to the other surface 224 bof the EL-device substrate 224, and then, presses the color filtersubstrate 222 by the pressing member 247 from the surface opposite tothe side where the color filter 232 is disposed, thereby bringing thecolor filter substrate and the EL-device substrate 224 into intimatecontact with each other. Consequently, the thermosetting resin 233dropped so as to convexly bulge is radially spread, so that thethermosetting resin 233 is filled in the gap between the substrates.

[0204] In the case where the thermosetting resin 233 is dropped, inaccordance with the rectangular EL-device substrate 224, as shown inFIG. 11A, the thermosetting resin 233 is dropped onto a plurality ofpoints (three points in this embodiment) at regular intervals along thecenter line A1 passing through the center, in the direction of thewidth, of the EL-device substrate 224 and extending in the direction ofthe length. When the substrates 221 and 222 are opposed to each otherand pressed in a direction that decreases the distance therebetween, thetops of the convex resin portions come into contact with the opposedsubstrate without fail, so that the convex resin portions are radiallyspread with the tops as the centers. Consequently, the resin is filledin the entire gap between the substrates. In the case where thethermosetting resin 233 is dropped not along a straight line but droppedalong two parallel lines as shown in FIG. 11B, when the portions ofresin dropped onto four adjacent points forming a square are spread, theresin is spread over the substrate surface with a gap being left at thecenter of the four points as shown in FIG. 11B and the air shut up inthe gap has nowhere to escape, so that the air is left between thesubstrates as a bubble. On the contrary, in this embodiment, by droppingthe thermosetting resin 233 along a straight line, no gap as shown inFIG. 11B is formed, so that the formation of bubbles is surelyprevented.

[0205] After the substrates 221 and 222 are brought into intimatecontact and the thermosetting resin 233 is filled into the gaptherebetween, the color filter substrate 222 is positioned by aligningthe electrode pattern of the first electrode 226 and the pattern of thecolor filter 232, and the photo-setting resin 240 is hardened byapplying ultraviolet rays to the portion where the photo-setting resin240 is placed, thereby temporarily fixing the color filter substrate 222and the EL device 221. Since the photo-setting resin 240 is placed onthe portion where the color filter 232 is not formed as mentionedpreviously, it never occurs that the ultraviolet rays are absorbed bythe color filter; the photo-setting resin 240 can surely be hardened totemporarily fix the color filter substrate 222 and the EL device 221.

[0206] Then, the filled thermosetting resin 233 is hardened. When theadhesive layer of the thermosetting resin 233 is thick, the viewingangle of the color EL display apparatus 220 is affected. However, sincethe thermosetting resin (FA Sealer) 233 used in this embodiment has ahigh viscosity of approximately 1500 to 3000 cps at an ordinarytemperature of 25° C., it is difficult to strongly spread thethermosetting resin 233 at the ordinary temperature.

[0207] The thermosetting resin 233 used in this embodiment decreases inviscosity by being heated. For example, at 100° C. which is atemperature immediately before the temperature at which thethermosetting resin 233 is thermally hardened, the viscosity isdecreased to approximately 100 cps or lower, and the thermosetting resin233 is thermally hardened at 110° C. Therefore, as shown in FIG. 12, thecolor EL display apparatus 220 is set on a jig capable of applying aforce onto the color filter 232 formed portion of the color filtersubstrate 222, and the whole of the color EL display apparatus 220 isplaced in an oven to thermally harden the thermosetting resin 233,whereby the thermosetting resin 233 can be hardened in a thinly spreadcondition. In this embodiment, in the jig that applies a force to thecolor filter 232 formed portion, under a condition where the color ELdisplay apparatus 220 is placed on a support 251 with the EL device 221side down, a weight 250 is placed on the color filter 232 formed portionof the color filter substrate 222 so that a pressure acts in a directionthat decreases the distance between the substrates 222 and 224. Such acolor EL display apparatus 220 is placed in an oven, and the oven isheated to 110° C. at which the thermosetting resin 233 is thermallyhardened. The thermosetting resin 233 decreases in viscosity while beingheated, and by the color filter formed portion being pressed by theweight 250, the resin 233 is thinly spread to fill the entire gapbetween the substrates. Thus, the resin 233 is thinly spread and isthermally hardened when the temperature of the thermosetting resin 233reaches 110° C., so that the color filter substrate 222 and the ELdevice 221 are completely bonded. At this time, since the EL device 221and the color filter substrate 222 are temporarily fixed in a positionedcondition, the device 221 and the substrate 222 are prevented from beingbonded in a displaced condition. The reason why the color filter 232formed portion of the color filter substrate 222 is pressed is thatsince the portion bonded by the photo-setting resin 240 has already beenhardened and the gap is maintained in the photo-setting resin portioneven during heating, when the weight 350 is placed over two points ofthe photo-setting resin 340 having been hardened, no pressure acts onthe central portion of the color filter substrate 322. Moreover, since aforce is applied to spread the resin after the viscosity of the resin isdecreased, a large force is unnecessary and the resin can easily bethinly spread.

[0208] Since the thermosetting resin 333 is thus hardened in a thinlyand uniformly spread condition, the thickness of the resin layer isdecreased, so that color displacements due to the viewing angle are notcaused. Moreover, since the thermosetting resin can be filled into thegap between the substrates without any bubbles being formed, imagequality degradation can also be prevented.

[0209] Lastly, the silicone resin 341 is filled into the gap between thecolor filter substrate 322 and the EL-device substrate 324 to completethe color EL display apparatus 320.

[0210]FIG. 13 is a plan view showing dropped positions of athermosetting resin 333 dropped onto an EL-device substrate 324 in acolor EL display apparatus manufacturing method according to a fifthembodiment of the invention. Since this manufacturing method is the sameas the method shown in FIG. 15 to FIGS. 19A and 19B except the droppedpositions, descriptions of the method are omitted.

[0211] With respect to the size of the EL-device substrate 324 used inthis embodiment, the lateral size L1 is 26 cm and the longitudinal sizeL2 is 8 cm. On such a rectangular EL-device substrate 324, thethermosetting resin 333 is dropped at each vertex of a zigzag line A2 asshown in FIG. 21. The distance L3 between the dropped positions of thethermosetting resin 333 adjoining in a longitudinal direction is 4 cm,and the distance L4 in a lateral direction is 2 cm. The inside bendangle θ of the line A2 being bent in zigzags is selected so as to fallwithin a range of 90°<θ≦180°. In the case where the bend angle θ is lessthan 90°, when the portions of the thermosetting resin 333 at threeadjoining points are radially spread, a gap is formed at the center ofthe three points, which causes a bubble. Moreover, that the bend angleis 180° means that the line A2 is a straight line.

[0212] Thus, by dropping the thermosetting resin 333 along a zigzagline, even when the EL-device substrate 324 is rectangular, thethermosetting resin can uniformly be spread and filled in the entire gapbetween the substrates.

[0213] The positions where the thermosetting resin 333 is dropped arenot limited to the vertices of the zigzag line A2 but the thermosettingresin may be dropped onto straight line portions. The line along whichthe thermosetting resin 333 is dropped is not limited to a zigzag linebut the thermosetting resin may be dropped along a wavy line. In thiscase, the angle formed by the resin portions at consecutive three pointsis also selected so as to fall within a range of 90°<θ≦180°, so that theresin can be filled in the gap between the substrates without anybubbles being formed.

[0214]FIG. 14 is a cross-sectional view showing a condition in which theEL device 221 and the color filter substrate 222 are bonded together ina color EL display apparatus manufacturing method according to a sixthembodiment of the invention. The method of this embodiment is differentfrom the color display apparatus manufacturing method shown in FIGS. 8to 12 only in the bonding method. Therefore, descriptions of the samemanufacturing steps are omitted.

[0215] In this embodiment, the thermosetting resin is dropped so as tobe convexed not only onto three points on the EL-device substrate 224,but also onto three points on the color filter 232 of the color filtersubstrate 222. The thermosetting resin is dropped onto positions wherewhen the substrates 222 and 224 are bonded together, the tops of theportions of the thermosetting resin 233 dropped so as to be convexed arein contact with each other. By thus bringing the substrates 222 and 224into intimate contact so that the tops of the resin portions are incontact with each other, the resin is radially spread with the tops asthe centers, and the resin can be filled in the gap between thesubstrates without any bubbles being formed. By thus bonding thesubstrates 222 and 224 so that a pair of resin portions are in contactwith each other, the dropping amount per position can be reduced whenthe filling amount is the same, so that the thermosetting resin cansuitably be dropped so as to be convexed without the dropped resin beingspread. In this embodiment, the resin dropped positions are not limitedto positions along a straight line; the resin may be dropped along azigzag line on both the color filter substrate 222 and the EL-devicesubstrate 224. In this case, the color filter substrate 222 and theEL-device substrate 224 are brought into intimate contact so that thetops of the portions of the dropped thermosetting resin are in contactwith each other.

[0216] As yet another mode of the embodiment of the invention, forexample, in a method of manufacturing a square color EL displayapparatus, the display apparatus may be manufactured by dropping thethermosetting resin onto one point at the center of the EL-devicesubstrate 224 and bringing the color filter substrate and the EL-devicesubstrate into intimate contact. Further, the display apparatus may bemanufactured by dropping the thermosetting resin onto the center of bothof the filter substrate 222 and the EL-device substrate 224 and bringingthe substrates 222 and 224 into intimate contact so that the tops of theresin portions are in contact with each other.

[0217] In the above-described embodiments, after the photo-setting resinis placed on the color filter substrate 222, the substrates 222 and 224are brought into intimate contact. However, as still another mode of theembodiment of the invention, the display apparatus may be manufacturedby filling the photo-setting resin 240 into the gap between theEL-device substrate 224 and the color filter substrate 222 after thesubstrates 222 and 224 are brought into intimate contact with eachother, and hardening the resin by applying ultraviolet rays. In theabove-described embodiments, the number of drops of the thermosettingresin for each position is not limited to one but several drops of resinmay be applied to one position so as to convexly bulge. Thereby, theresin filling amount can be increased.

[0218]FIG. 15 is a cross-sectional view showing a color EL displayapparatus 320 manufactured by a light-transmitting substrate bondingmethod according to a seventh embodiment of the invention.

[0219] The color EL display apparatus 320 comprises an EL device 321 anda color filter substrate 322 bonded together. The EL device 321comprises a light-transmitting EL-device substrate 324, an EL deviceportion 323 and a sealing portion 325. The color filter substrate 322comprises a light-transmitting substrate 331 and a color filter 332.

[0220] The EL device 321 is a double-insulation-type thin-film EL devicein which a first electrode 326, a first insulation film 327, a lightemission layer 328, a second insulation film 329 and a second electrode330 constituting the EL device portion 323 are successively laminated onthe EL-device substrate 324 made of glass. To form the first electrode326, ITO (indium-tin oxide) is deposited on one surface 324 a of theEL-device substrate 324 in a thickness of approximately 200 nm by theelectron beam vapor deposition method or the high-frequency sputteringmethod, and the first electrode 26 is formed in stripes by wet etchingusing a photoresist.

[0221] The first insulation film 327 laminated on the first electrode326 comprises a lamination of an SiO₂ film with a thickness ofapproximately 40 nm and an Si₃N₄ film with a thickness of approximately220 nm, and is formed by the high-frequency sputtering method. As thelight emission layer 328, a ZnS:Mn layer is formed in a thickness ofapproximately 7000 Å by the electron beam vapor deposition method usinga ZnS:Mn pellet as the evaporation source. The EL light emission layer328 emits yellow light including red to green light emission ranges byapplying an alternating field between the first and the secondelectrodes 326 and 330, and by dividing the light into spectra by redand green color filters, a multicolor EL display apparatus of red andgreen can be produced.

[0222] The reason why the light emission layer 328 is used in thisembodiment is that a monochrome EL display apparatus using this lightemission layer has already been put to practical use and it has beenconfirmed that the material of the light emission layer is excellent inlight emission brightness and light emission stability. The color ELdisplay apparatus embodying the invention is not limited to such amulticolor EL display apparatus of red and green, but a full-color ELdisplay apparatus can be produced, for example, by driving into spectrawhite EL light emitted from a lamination of ZnS:Mn and SrS:Ce lightemission layers by color filters of red, green and blue.

[0223] The second insulation film 329 laminated on the light emissionlayer 328 comprises a lamination of an Si₃N₄ film with a thickness ofapproximately 100 nm and an SiO₂ film with a thickness of approximately35 nm. These films are formed by the high-frequency sputtering method.After the formation of the second insulation film 329, high vacuumannealing is performed in order to improve the crystallinity of thelight emission layer 328. The high vacuum annealing is performed at 630°C. in a high vacuum of not more than 1×10⁻¹⁴ Pa.

[0224] Lastly, as the second electrode 330, Al is deposited in athickness of approximately 500 nm by heat vapor deposition, and thesecond electrode 330 is formed in stripes perpendicular to the firstelectrode by wet etching using a photoresist, so that the EL deviceportion 323 is completed.

[0225] To form the moistureproof sealing portion 325 of the EL device321, a protective glass 342 where digging processing is performed to adepth T1 of approximately 1 mm is disposed so that the EL device portion323 is sealed in the portion where the digging processing is performed,and the periphery of the protective glass 342 is bonded onto the onesurface 324 a of the EL-device substrate 324 by use of an epoxy resin338. Then, silicone oil mixed with silica gel is filled into a sealedspace 337 where the EL device portion 323 is sealed through an oilintroduction hole 335 formed in the protective glass 342 in advance, andthe introduction hole is closed by a sealing glass 336. In the casewhere silicone oil is filled, under a condition where the sealed space337 is evacuated by exhausting air in the sealed space 337 through theoil introduction hole 335, silicone oil is absorbed through the oilintroduction hole 335 so that the sealed space 337 is filled withsilicone oil. Thus, since it is necessary that the sealed space 337 beevacuated when oil is filled, the EL-device substrate 324 has athickness that endures such a vacuum when oil is filled.

[0226] After the EL device portion 323 and the moistureproof sealingportion 325 are formed on the EL-device substrate 324, by etching usinghydrofluoric acid, a concave portion 344 is formed in the EL-devicesubstrate 324 so that the thickness T2 of the portion of the EL-devicesubstrate 324 opposed to the EL device portion 323 is approximately 100μm. At this time, in view of the mounting of the color EL displayapparatus 320, only the portion where the color filter substrate 322 isfitted is etched into a concave so that the periphery of the EL-devicesubstrate 324 is left in a frame shape. Since the EL-device substrate324 interposed between the EL device portion 323 and the color filter332 is thinned by etching, the distance between the first electrode 326of the EL device portion 323 and the color filter 332 decreases.Consequently, the viewing angle deterioration due to color displacementscan be prevented, so that a large viewing angle can be ensured.

[0227] The methods of mounting the color filter 332 include thefollowing: a method in which the color filter 332 is directly formed onthe other surface 324 b which is the bottom surface of the concaveportion 344 of the EL-device substrate 324, and the substrate 331 isbonded thereonto; and a method in which the substrate 331 where thecolor filter 332 is formed is bonded to the other surface 324 b of theEL-device substrate 324. According to the latter method, since anadhesive layer is interposed between the color filter 332 and theEL-device substrate 324, the thickness of the adhesive layer affects theviewing angle. According to the former method, it is necessary todirectly form the color filter 332 on the other surface 324 b of theEL-device substrate 324 which is the bottom surface of the concaveportion 344, and the production of the color filter 332 is difficult.Therefore, this embodiment employs the latter method where theproduction of the color filter 332 is easier.

[0228] The color filter 332 of the color filter substrate 322 comprisesred and green filters R and G alternately arranged on alight-transmitting glass substrate 331 a. Black filters Bk are formedbetween the filters R and G. The color filter substrate 322 and theEL-device substrate 324 of the EL device 321 are bonded together byfilling a thermosetting synthetic resin 333 into the gap between thecolor filter 332 side surface of the color filter substrate 322, thatis, the surfaces of the filters R, G and BK opposed to the other surface324 b of the EL-device substrate 324 and the one surface 331 a of thesubstrate 331, and the other surface 324 b of the EL-device substrate324. The one surface 331 a of the substrate 331 where the color filter332 is not disposed and the EL-device substrate 324 are fixed at notless than two points (at the left and right ends of the substrate 331 inFIG. 15) by a photo-setting resin 340. The gap between the color filtersubstrate 322 and the EL-device substrate 324, that is, the periphery ofthe color filter substrate 322 is filled with a silicone resin 341.Thus, the color filter substrate 322 and the EL device 321 are bondedtogether with a great strength.

[0229] Subsequently, the general outline of the method of bonding thecolor filter substrate 322 and the EL-device substrate 321 will beshown. First, as shown in FIG. 16, the color filter substrate 322 andthe EL device 321 are prepared, and onto the surface of the color filter332 of the color filter substrate 322, spacers 350 comprising, forexample, adhesive beads are fixed. Then, a plurality of drops of aliquid thermosetting resin 333 is applied so as to convexly bulge in aconical shape having one convex portion as shown in FIG. 16. The resin333 has no bubbles mixed therein, and has a viscosity of a degree suchthat the resin does not thinly spread when dropped and that the resindoes not drop when the color filter substrate 322 is overturned when thesubstrates are brought into intimate contact as described later. On thecolor filter substrate 322, the photo-setting resin 340 is placed on atleast two points of the portion of the one surface 331 a of thesubstrate 331 where the color filter 332 is not disposed.

[0230] To fix the spacers 350, adhesive beads (adhesive spacersCBS-20725, CB-210, manufactured by Sekisui Fine Chemical) with a graindiameter of 7.25 μm or 10 μm are sprayed onto the color filter 332, andthen, the color filter 332 is heated in an oven at 150° C. for 20minutes to fix the spacers 350. At this time, the beads spraying densityis 15 per 1 mm².

[0231] As the resin 333, a thermosetting resin (a thermosetting resinprototype manufactured by Mitsui Chemicals Inc.) was used. Since theresin has a viscosity of 2000 cps at an ordinary temperature, it is easyto drop the resin so as to convexly bulge, and the resin can beprevented from easily dropping when the color filter substrate 322 isoverturned. Further, since the viscosity of the resin is decreased toapproximately 100 cps at the time of heating, the resin is smoothlyspread in the gap between the substrates.

[0232] Since the color filter substrate 322 has a rectangular form withdimensions of 25 cm×8 cm (the area is 200 cm²) as shown in FIG. 17, theresin 333 is dropped onto 16 points along a zigzag line in the directionof length of the color filter substrate 322 as shown in the figure. Atthis time, the distance between dropped points adjoining in thedirection of the length is 3 cm, and the width W of the zigzag is 1.5cm. The dropping amount per point is 0.015 to 0.03 cc. With the droppingamount of this degree, the resin 333 is surely prevented from droppingwhen the color filter substrate 322 is overturned.

[0233] Then, the EL device 321 and the color filter substrate 322 arebrought into intimate contact by an intimate contact jig 346 shown inFIG. 18. The intimate contact jig 346 has an EL substrate support 345and a pressing portion 347. First, the EL-device substrate 324 is placedon the EL substrate support 345 with the other surface 324 b facingupward, and then, the color filter 322 is overturned so that the colorfilter 332 of the color filter substrate 322 is opposed to the othersurface 324 b of the EL-device substrate 324. By thus overturning thecolor filter substrate 322, the dropped resin 333 further bulgesconvexly by its own weight, so that the resin 333 can be filled in thegap between the substrates 324 and 331 without any bubbles being formed.

[0234] When the color filter substrate 322 is placed on the EL-devicesubstrate 324 to bond the substrates 322 and 324 together, the colorfilter substrate 322 is positioned by aligning the electrode pattern ofthe first electrode 326 of the EL device 323 of the EL-device substrate324 and the pattern of the color filter 332 of the color filtersubstrate 331, and the photo-setting resin 340 is hardened by applyingultraviolet rays to the portion where the photo-setting resin 340 isplaced under a condition where the portion of the photo-setting resin340 is pressed by the pressing member 347, thereby temporarily fixingthe color filter substrate 322 and the EL device 321. Since thephoto-setting resin 340 is placed on the portion where the color filter332 is not formed as mentioned previously, it never occurs that theultraviolet rays are absorbed by the color filter 332; the photo-settingresin 340 can surely be hardened to temporarily fix the color filtersubstrate 322 and the EL device 321.

[0235] Then, the pressing member 347 is separated, and the color filter322 and the EL-device substrate 321 being temporarily fixed are placedin an oven as they are to harden the thermosetting resin 333. The ovenin which the EL-device substrate 324 and the color filter substrate 322being temporarily fixed are placed is heated first at 80° C. for 20minutes. The resin 333 used in this embodiment does not harden at 80° C.and is decreased in viscosity to approximately 100 cps.

[0236] When the EL-device substrate 321 and the color filter substrate322 are bonded together, since the temperature is an ordinarytemperature, the resin 333 is high in viscosity and convexly bulges.Moreover, since the EL-device substrate 324 is etched so that itsthickness T2 is approximately 100 μm in order to prevent the viewingangle from deteriorating, at the point of time when the color filtersubstrate 322 and the EL-device substrate 324 are bonded together fortemporarily fixing, the EL-device substrate 324 is concaved anddistorted at the portion where the resin 333 is dropped. Moreover, thespacers 350 are interposed between the color filter substrate 332 andthe EL-device substrate 324, so that the distance between the colorfilter substrate 331 and the EL-device substrate 324 is prevented frombeing smaller than a predetermined value.

[0237] When the substrates 322 and 321 are heated to 80° C. in the ovenunder this condition, the resin 333 is decreased in viscosity toapproximately 100 cps. Then, as shown in FIG. 19A, a capillaryphenomenon is caused in the gap between the color filter substrate 322and the EL-device substrate 324 by the surface tension at the surface ofthe resin 333 having been decreased in viscosity, so that the resin 333having been decreased in viscosity is spread in the gap between thesubstrates 322 and 324. Since the surface tension causes a force to actin a direction that brings the color filter substrate 322 and theEL-device substrate 324 into intimate contact, the resin 333 is spreadin the gap between the substrates 322 and 324 without any external forcebeing exerted on the substrates 322 and 324. Moreover, although theEL-device substrate 324 is concaved and distorted at the resin droppedportion when the substrates are bonded together, by the spread of theresin 333 to the periphery due to the capillary phenomenon and the forcethat acts in the direction that brings the substrates 322 and 324 intointimate contact with each other, the resin 333 in the concaved portionat the resin dropped portion is successively discharged to the peripheryas shown in FIG. 19B. The concave at the resin dropped portion is thuseliminated, so that the EL-device substrate 324 becomes flat. As aresult, the display screen is prevented from being distorted.

[0238] The resin 333 cannot be filled into the gap between the colorfilter substrate 332 and the EL-device substrate 324 when the substrates322 and 324 are in absolute contact with each other. However, in thisembodiment, the substrates 322 and 324 are prevented from being broughtinto absolute contact by interposing the spacers 350 therebetween, sothat the resin 333 having been decreased in viscosity can smoothly bespread in the gap between the substrates 322 and 324.

[0239] When local concave portions are formed in the surfaces of theopposed substrates 322 and 324, there are cases where bubbles are formeddue to the difference in speed of spread of the resin 333 between at thelocal concave portions P and at the periphery thereof as described withreference to FIG. 21. This occurs when the distance between thesubstrates 322 and 324 largely differs between at the concave portions Pand at the periphery thereof. Therefore, the formation of bubbles can beprevented by decreasing the difference between the distance between thesubstrates 322 and 324 at the local concave portions P and the distancebetween the substrates 322 and 324 at the periphery. That is, byincreasing the grain diameter of the spacers 350 interposed between thesubstrates 322 and 324, the difference between the distance at theconcave portions P and the distance at the periphery can be reduced tosuppress the formation of bubbles.

[0240] In this embodiment, two kinds of spacers were prepared by usingthe spacers 350 comprising two kinds of beads with grain diameters of7.25 μm and 10 μm, and using these two kinds of spacers 350, bonding wasperformed with the amount of resin filled into the gap between thesubstrates 322 and 324 being 0.32 cc (0.02 cc per drop, 16 drops wereapplied). Although bubbles were formed when the beads with a graindiameter of 7.25 μm were used, no bubbles were formed when the beadswith a diameter of 10 μm were used. From this, it was found that the useof beads with a grain diameter of not less than 10 μm is effective inpreventing the formation of bubbles. When the grain diameter of thespacers is not less than 100 μm, the distance between the color filtersubstrate 322 and the EL-device substrate 324 is increased, so that itis difficult to spread the resin 333 by use of the capillary phenomenonand the distance between the EL device portion 323 and the color filter332 is increased to deteriorate the viewing angle.

[0241] The resin 333 inserted between the substrates 322 and 324 spreadsdue to the capillary phenomenon, and a force acts on the substrates 322and 324 in the direction that brings the substrates 322 and 324 intointimate contact with each other in the process of spread of the resin,so that the distortion caused when the substrates 322 and 324 are bondedtogether is eliminated. However, when the spread resin reaches to theperiphery of the color filter substrate 322, the spread of the resin 333due to the capillary phenomenon stops, so that the distortion of theEL-device substrate 324 is not eliminated. Consequently, the displayquality deteriorates. This problem occurs when the amount of the resininserted between the substrates 322 and 324 is too large. When theamount of the inserted resin is too small, it is impossible to spreadthe resin so as to fill the entire gap between the substrates 322 and324. The display quality also deteriorates in this case.

[0242] In the above-described manufacturing method, using the spacers350 comprising beads with a grain diameter of 10 μm, bonding wasperformed with the amount of the resin inserted between the substrates322 and 324 being 0.28 cc, 0.32 cc, 0.40 cc and 0.44 cc (16 drops wereapplied in all cases). When the amount of the resin was 0.44 cc, asomewhat conspicuous distortion was found. From this, it is desirablethat the amount of the resin inserted between the substrates 322 and 324be less than 0.44 cc. Therefore, when the area of the region between thesubstrates 322 and 324 to be filled with the resin is S (in thisembodiment, S is the area of one surface of the color filter substrate322 opposed to the other surface 324 b of the EL-device substrate 324)and the grain diameter of the spacers is d, it was found that it isdesirable that the amount D of the resin inserted between the substrates(in this embodiment, D is the total amount of the resin dropped onto thecolor filter substrate 322) satisfy the following condition:

D<S·(d+12 μm).

[0243] In this embodiment, S=200 cm², d=10 μm, and D=0.44 cc.

[0244] Since the lower limit of the resin amount D when thesubstrate-to-substrate distance is d and the resin is spread over thearea S is S·d, it is desirable that the amount D of the inserted resinsatisfy the following condition:

S·d<D<S·(d+12 μm).

[0245] The invention may be embodied in other specific forms withoutdeparting from the spirit or essential characteristics thereof. Thepresent embodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription and all changes which come within the meaning and the rangeof equivalency of the claims are therefore intended to be embracedtherein.

What is claimed is:
 1. A method of manufacturing a color EL displayapparatus comprising the steps of: forming a plurality of EL devices inwhich an EL light emission layer is interposed between a pair ofelectrodes, on one surface of a first light-transmitting substratehaving a thickness larger than a predetermined reference thickness;attaching a second substrate to the one surface of the first substratewith a predetermined gap in between; filling a material for protectingthe EL devices, into a gap between the one surface of the firstsubstrate and the second substrate; processing the first substrate so asto have the reference thickness; and attaching color filters eachcapable of transmitting light of a predetermined wavelength to the othersurface of the first substrate.
 2. The method of manufacturing a colorEL display apparatus of claim 1, wherein the reference thickness is notmore than 1.2 times the width of an interval between one electrodes ofthe pairs of electrodes in two adjacent EL devices.
 3. The method ofmanufacturing a color EL display apparatus of claim 1, wherein thereference thickness is not less than 25 μm and not more than 200 μm. 4.The method of manufacturing a color EL display apparatus of claim 1,wherein the reference thickness is not less than 50 μm and not more than100 μm.
 5. The method of manufacturing a color EL display apparatus ofclaim 1, wherein the second substrate has a thickness of 0.8 mm or more.6. The method of manufacturing a color EL display apparatus of claim 1,further comprising a step of attaching a third light-transmittingsubstrate to the other surface of the first substrate with the colorfilters in between.
 7. The method of manufacturing a color EL displayapparatus of claim 1, wherein the third substrate has a thickness of 0.5mm or more.
 8. A method of manufacturing a color EL display apparatus,comprising the steps of: preparing EL devices in which a firstlight-transmitting electrode, an EL light emission layer and a secondelectrode are formed on one surface of a light-transmitting EL-devicesubstrate and EL light is emitted from the other surface of theEL-device substrate, and a color filter substrate where color filtersare disposed on one surface of a light-transmitting substrate, andfilling a thermosetting resin into a gap between the other surface ofthe EL-device substrate and the surface of the color filter substratewhere the color filters are disposed, and then thermally setting thethermosetting resin to bond the color filter substrate and the EL-devicesubstrate.
 9. A method of bonding two substrates at least one of whichis a light-transmitting substrate, the method comprising the steps ofdropping a liquid hardening resin on one substrate so as to convexlybulge, and subsequently bring the two substrates into intimate contactso that the liquid hardening resin is spread to fill a gap between thesubstrates and be hardened.
 10. A method of bonding two substrates atleast one of which is a light-transmitting substrate, comprising thesteps of: dropping a liquid hardening resin onto each of the twosubstrates so as to convexly bulge, and subsequently bring the twosubstrates into intimate contact so that tops of resin portions on thesubstrates are in contact with each other and the liquid hardening resinis spread to fill a gap between the substrates and is hardened.
 11. Amethod of bonding two substrates at least one of which is alight-transmitting substrate, comprising the steps of: dropping a liquidhardening resin onto one substrate at a plurality of points along astraight line or a zigzag line; and subsequently bringing the twosubstrates into intimate contact so that the liquid hardening resin isspread to fill a gap between the substrates and is hardened.
 12. Themethod of manufacturing a color EL display apparatus of any one ofclaims 9 to 11, wherein when being heated, the liquid hardening resinhas a viscosity lower than that at an ordinary temperature, and a forceis exerted on the substrates so that the resin between the substrates isspread while the substrates are being heated.
 13. The method ofmanufacturing a color EL display apparatus of claim 8, wherein when theEL-device substrate and the color filter substrate are bonded together,a liquid thermosetting resin is dropped on one substrate so as toconvexly bulge, the two substrates are brought into intimate contact sothat the thermosetting resin is spread to fill the gap between thesubstrates, the substrates are fixed by a photo-setting resin at aportion where color filters are not disposed under a condition where theEL-device substrate and the color filter substrate are positioned, andthen, the substrates are heated to harden the thermosetting resin,thereby bonding the two substrates.
 14. The method of manufacturing acolor EL display apparatus of claim 8, wherein when the EL-devicesubstrate and the color filter substrate are bonded together, athermosetting resin is dropped onto each of the substrates so as toconvexly bulge, the two substrates are brought into intimate contact sothat tops of resin portions on the substrates are in contact with eachother to thereby spread the thermosetting resin to fill the gap betweenthe substrates, the substrates are fixed by a photo-setting resin at aportion where the color filters are not disposed under a condition wherethe EL-device substrate and the color filter substrate are positioned,and then, the substrates are heated to harden the thermosetting resin,thereby bonding the substrates.
 15. The method of manufacturing a colorEL display apparatus of claim 8, wherein when the EL-device substrateand the color filter substrate are bonded together, a thermosettingresin is dropped so as to convexly bulge on one substrate at a pluralityof points along a straight line or a zigzag line, the two substrates arebrought into intimate contact to spread the thermosetting resin so as tofill a gap between the substrates, the substrates are fixed by aphoto-setting resin at a portion where the color filters are notdisposed under a condition where the EL-device substrate and the colorfilter substrate are positioned, and then, the substrates are heated toharden the thermosetting resin, thereby bonding the substrates.
 16. Themethod of manufacturing a color EL display apparatus of any one ofclaims 13 to 15, wherein the liquid thermosetting resin is lower inviscosity when heated than at an ordinary temperature, and when thesubstrates are heated, a force is exerted on the substrates so that theresin between the substrates is spread.
 17. A method of bonding twosubstrates at least one of which is a light-transmitting substrate,comprising the steps of: dropping a liquid hardening resin on a surfaceof one substrate so as to convexly bulge, directing the surface wherethe resin is dropped, downward so as to face a surface of the othersubstrate, and bonding the substrates to each other so that the resin isspread to fill a gap between the substrates and is hardened.
 18. Amethod of bonding two substrates at least one of which is alight-transmitting substrate, comprising the steps of: interposing aliquid hardening resin between the substrates, spreading the liquidhardening resin between the substrates by use of a capillary phenomenonof the resin, and hardening the resin thereafter.
 19. The method ofmanufacturing a color EL display apparatus of claim 17 or 18, whereinthe liquid hardening resin is a thermosetting resin, and a viscosity ofthe resin at an ordinary temperature is higher than that of the resinthermally hardened.
 20. The method of manufacturing a color EL displayapparatus of any one of claims 9 to 11, wherein a spacer of apredetermined grain diameter is interposed between the substrates. 21.The method of manufacturing a color EL display apparatus of claim 20,wherein the spacer is fixed to the surface of one substrate in advance,and the substrates are bonded together thereafter.
 22. The method ofmanufacturing a color EL display apparatus of claim 20, wherein thegrain diameter of the spacer is not less than 10 μm.
 23. The method ofmanufacturing a color EL display apparatus of claim 20, wherein when anarea of a range between the substrates to be filled with the resin is Sand the grain diameter of the spacer is d, an amount D of the liquidhardening resin inserted between the substrates is selected so as tofall within the following range: S·d<D<S·(d+12 μm).
 24. The method ofmanufacturing a color EL display apparatus of claim 17, wherein one ofthe two substrates is a light-transmitting EL-device substrate, thelight-transmitting El-device substrate having a first light-transmittingelectrode, an EL light emission layer and a second electrode formed onone surface thereof, and emitting EL light from the other surface; andthe other substrate of the two substrates is a light-transmitting colorfilter substrate and having color filters disposed on one surfacethereof.